Retailers manage stronger-than-expected sales in June

— -- Tax rebates, sunny weather and store promotions helped retailers post stronger-than-expected sales in June, but some question whether the gains will extend into the crucial back-to-school season.

The last big batch of tax-rebate checks is in the mail Friday. How big their impact will be — and how long it will last — isn't entirely clear. Gap, which reported a 7% decline in same-store sales, better than the 11.6% drop that was forecast, says it can't directly tie its sales results to the tax rebates, says spokeswoman Kris Marubio.

"The tax rebates that gave discount retailers a big boost in June will remain the driver of consumer shopping for the next few months," Frank Badillo, senior economist at TNS Retail Forward, said in a statement. "Strip out the tax rebates, and shoppers are in pretty bad shape."

The rebate boost may not linger much longer, warns Sarah Henry, an analyst at MFC Global Investment Management.

"There may be a bit of spillover in July," she says. "I think once we get to the back-to-school season, which starts in August, it will be more of a true measure of the shopper."

Michael Brown, a retail strategist at consulting firm Kurt Salmon Associates, agrees that the effect of the rebate checks will likely extend for only about a month more. But he holds out some optimism.