A shopper exits a Wal-Mart store during a winter storm in Philadelphia on December 19, 2009. (Matt Slocum/AP file)

Wal-Mart has a new deal for you.

It’s going to check competitor prices and refund the difference to customers if they would have paid less elsewhere. But the deal might not be as good as it sounds.

For one thing, you don’t really get your money back. If a competitor is charging less for an item you bought at Wal-Mart, the difference in price is loaded onto a gift card that you can only use at Wal-Mart.

Chances are you’ll end up spending that 37 cents you saved on something that costs more than 37 cents which means you ultimately end up spending more at Wal-Mart, not less.

However, you don’t have to spend your refund at once. Wal-Mart’s new “Savings Catcher” tool lets you build up refund money and spend it later if you want.

Here’s how it works: customers log in to the “Savings Catcher” after making a purchase and enter a number from their receipt. According to Wal-Mart’s website: “Savings Catcher compares the prices of the items you bought at Walmart to the advertised prices at the time of your purchase from the print and online versions of weekly print ads of top retailers in your area.”

First of all, the internet doesn’t count as one of the “top retailers in your area,” so you don’t get a dime if the dish soap and cat litter you bought at Wal-Mart are cheaper online.

And by “top retailers in your area” Wal-Mart is referring to the ones that weren’t already shut down by the arrival of Wal-Mart.

A 2008 study published in the Journal of Urban Economics looked at the impact of 3,000 Wal-Mart store openings nationwide and found that 150 jobs are lost on average because competing businesses close or downsize.

The tool compares Wal-Mart’s prices on 80,000 food and household items, the Associated Press reports. But there are some caveats. The tool doesn’t compare prices for weighed items like produce and meat, which can represent a big chunk of a family’s grocery budget. Clothes and electronic gadgets also aren’t eligible.

You only get a refund if the competitor’s lower price was advertised at the time of your purchase, so you can’t get a refund on cereal you bought at Wal-Mart on Thursday if the competitor didn’t put it on sale until Friday.

Price matching isn’t a new idea. Target, one of Wal-Mart’s competitors, will even match online competitors’ prices, which Walmart’s Savings Catcher tool doesn’t do. What’s different about Wal-Mart’s new tool is that the store, not the customer, is doing the legwork to figure out if a better deal exists.

Wal-Mart Executive Vice President Duncan Mac Naughton told the AP that preliminary data shows that in the cities that have the Savings Catcher already, shoppers are putting more items in their basket and the checkout lines are faster because people don’t feel like they have to pull out their smartphones or circular ads to check prices.

Savings Catcher was rolled out earlier this month in seven major markets: Charlotte, Lexington, Dallas, San Diego, Hunstville, Minneapolis and Atlanta.

The new tool could help Wal-Mart hang on to customers feeling a financial squeeze due to a reduction in the food stamp program, which the company cited as one of the reasons (winter weather was another) behind its fourth consecutive quarter of declines in revenue at stores that have been open for at least a year in February.

Ken Perkins, president of retail research firm Retail Metrics LLC, told the AP that the Wal-Mart’s move will “put pressure on everyone else to follow suit.”