Holiday shoppers such as Amber Fields are the reason for the explosion of checkout charity. When a cash register clerk asks her to round up her bill to the nearest dollar and donate the rest to a charity, she doesn't hesitate to say "yes."

Those nickel-and-dime donations are adding up to millions of dollars at businesses ranging from Petco to J.C. Penney, providing a boost to nonprofits' fundraising and to the stores' public image.

Hardly chump change, checkout fundraisers across the nation raked in more than $348 million in 2012, according to an analysis of the 63 largest campaigns by Cause Marketing Forum.

"When it comes to kids, animals, the homeless — how do you say no to that?" asked Fields, a 36-year-old mother from Mound, shopping at Ridgedale Center last week.

"Change sits at the bottom of my purse. Why not give it to charity?"

The campaigns take various forms. There's the dollar round-up version, the coin collection box next to the cash register, or a donation request made by the cashier or on a credit-card screen. Customers may also be asked if they want to "purchase" a paper icon, such as a Children's Miracle Network balloon.

The full impact of these campaigns hadn't been calculated until last year, when the New York-based Cause Marketing Forum released an analysis of the 63 campaigns in 2012 that raised more than $1 million. The top three were:

• $54 million from eBay to more than 22,000 nonprofits.

• $41 million from Wal-Mart and Sam's Club for Children's Miracle Network Hospitals.

• $27.9 million from McDonald's for Ronald McDonald House charities.

Other top campaigns included those run by Safeway stores, Costco, Walgreens, Kmart, Lowe's, Pizza Hut and CVS Pharmacy.

"The data collected is just the tip of the iceberg," said the report, which estimates there were "hundreds of smaller campaigns fielded by businesses large and small, each of which raised thousands to hundreds of thousands of dollars annually."

Nuisance or not?

Shoppers grabbing last-minute gifts at Ridgedale had mixed reactions to the trend.

Fields said she liked being able to donate small amounts of money to different causes, because "it's not going to break the bank."

And it's simple for her and the charity, she said. Unlike many charity fundraisers, it doesn't require staffing, volunteers, overhead and thank you notes.

Linda Ament was more discerning. She and her husband already make substantial donations to their favorite charity. Said Ament: "I want to feel empathetic, but every place you walk into, it seems to be there."

Like many shoppers, she also admits feeling a bit of pressure. "It's kind of embarrassing if you're buying all this stuff, and you can't give to the less fortunate."

Bryna Pasco and her mom, Linda Pasco, of Maple Grove, have less trouble saying no. Linda Pasco said she would rather make a few big donations that have an impact than a dozen little ones.

"A 75 cents here, 75 cents there, I have no interest in that," she said.

Bryna Pasco has other reasons. "Even if it's change, I want to make sure it's in line with my values."

The boom in point-of-purchase charity is no surprise to Bruce Nustad, president of the Minnesota Retailers Association. He said the business community has long supported community projects and charities, but that support was not always visible.

The original checkout campaigns were mainly for large national corporations, he said, with proceeds going to national charities.

"Now, thanks to technology, it's gotten easy," said Nustad. "Main Street retailers can participate, and you can give to community organizations you're familiar with."

Minnesota campaigns

Cub Foods, for example, reports that it raised $100,000 this year during its October fundraiser for Second Harvest food bank based in St. Paul.

Chuck and Don's pet stores, based in Mahtomedi, raised $97,000 last year during the company's holiday "Paw Print" fundraiser, to support projects including pet oxygen masks for fire departments in the communities it serves.

That's up from $1,800 in 2005 when the check-out campaign was started.

"It builds a sense of community," said Karin Burseth, Chuck and Don's events coordinator. "It lets our customers know the causes we support."

But customers don't want to be hit up too often, she said, which is why Chuck and Don's shortened its holiday fundraiser this year by four weeks.

J.C. Penney also learned that it's best to limit exposure. After years of supporting a single broad cause — before- and after-school projects — during certain months, it launched charity-of-the-month campaigns two years ago. The company has gone back to seasonal campaigns, and is holding focus groups and surveys to narrow down a single key direction, said Kate Coultas, a company spokeswoman.

"One of the key lessons that we learned from 2012 and 2013 is that customers were not wanting to round up every single month or every single time they shopped at J.C. Penney," Coultas said. "The campaign began to lose steam so to speak when it became an everyday occurrence rather than a special opportunity a few times a year."

Still, J.C. Penney raised nearly $2 million for military families last holiday season, she said. The company kicked in $300,000, and employees donated another $100,000.

That kind of matching donation is something customers should watch for, said Jeremy Wells, president of the Minnesota chapter of the Association of Fundraising Professionals.

Checkout charity can be "misleading," he said, because businesses can take credit for their customers' generosity.

Wells considers checkout charity to be a mixed bag.

"It exposes organizations to people they would never find on their own," he said. "They'd never get exposure to the number of people at Kmart, Costco, Penney's."

But checkout donations "don't engage people in the act of philanthropy," he said. Donors typically don't research a charity's mission, volunteer or support in other ways. Said Wells: "You can't cultivate donors."

That said, donors not excited about follow-up calls may appreciate anonymity.

"I don't think nonprofits necessarily want a bunch of people donating anonymously," he said, "but I'm sure there are people who like that."

Jean Hopfensperger • 612-673-4511