Leaving the store with a receipt and shopping bags in hand doesn't mean that the sale is final. In fact, at many retailers, you can still reap savings on your purchases long after the initial transaction is complete, thanks to something called a price-adjustment policy.

Price adjustment policies allow a shopper to receive a refund should the item they buy go on sale one or two weeks after they've purchased it. These policies aren't anything new. But now there are more opportunities to take advantage of them as struggling retailers offer more sales and other discounts to lure in shoppers.

Why are the retailers being so generous? Call it desperation. September retail sales were down 1.2% -- the biggest year-over-year decline in three years, according to the Commerce Department. And the upcoming holidays aren't expected to provide the coveted sales boost retailers depend on each year. The National Retail Federation predicts holiday spending will inch just 1.9% higher this year.

To take advantage of a store's price adjustments (see chart below for a look at some the major retailers' policies), you'll need your receipt and the help of these insider shopping tips:

Shop on Friday
Because stores make most markdowns on Fridays in preparation for weekend sales, shopping late in the week improves your odds of being able to take advantage of the price adjustment policy, says Kathryn Finney, author of "How to Be a Budget Fashionista."

Use tracking sites
Track your purchases at free deal-generating sites that notify you if a given item's price drops within the time period selected. PriceProtectr.com monitors purchases through 146 retailers, including Best Buy and Staples, while comparison search engine PriceGrabber.com tracks specific items at hundreds of online retailers.

Pay with credit
Extended price adjustment policies are a little-known credit card perk. The Citi (C) Diamond Preferred Rewards card, for example, offers to refund the difference in price up to $250 if you spot a better deal within 60 days of purchase. The Fidelity (FSBI) Investment Rewards Visa (V) Signature card does the same.

Check for competitors' matches
It's harder to claim, but some stores will even match a competitor's price after you've made a purchase at their store. "But it's almost never done willingly and with a smile," says Edgar Dworsky, founder of consumer advocate site ConsumerWorld.org. "Be prepared for a bit of a battle." Bring the competitor's ad with you, as well as a printout of the store's price matching and adjustment policies.