NEW YORK – Shoppers are holding off on back-to-school shopping, and those who delay long enough might be rewarded with some steep discounts from desperate retailers.

Revenue at stores open at least a year — an industry measure of a retailer's health — rose 3.5 percent in July, the slowest pace since March, according to a tally of 11 retailers by the International Council of Shopping Centers. The figure, which excludes drugstores, was below a 5.5 percent increase in June.

Costco Wholesale Corp., typically a strong performer, was among the retailers reporting disappointing figures.

Many stores were already offering discounts and other come-ons to get shoppers to spend on the new shipments of fall clothing that started flowing in mid-July. But experts say even more deal are coming this month as stores try to boost sales for the back-to-school season, which runs from mid-July through mid-September.

"It was a lousy start," said Walter Loeb, a New York-based independent retail consultant. "There will be even more discounts to make up the sales."

Ken Perkins, president of research firm RetailMetrics, agrees.

"A vast number of shoppers are sticking to their shopping lists and are being very deal-driven," he said.

Only a sliver of retail chains now report monthly sales figures, and the list doesn't include Wal-Mart and many other large chains. But Thursday's tally adds to evidence that shoppers are being frugal about their purchases, particularly clothing.

On Monday, teen retailer American Eagle Outfitters Inc. slashed its second-quarter outlook because of weak traffic and sluggish sales of women's merchandise.

A clearer picture of how the back-to-school season is faring will emerge next week when major retailers like Wal-Mart Stores Inc. and Macy's Inc. report their second-quarter financial results.