Cashier error: Do I have to give it back?

This Deal of the Day comes from Kelli B. Grant at partner site SmartMoney.

Discovering that $20 has been knocked off a store receipt or deposited in your checking account isn’t quite the same as finding a crumpled $20 bill tucked in the pocket of last year’s spring jacket.

For starters, you do have an ethical obligation to point out the “found money,” says Margaret McLean, associate director of the Markkula Center for Applied Ethics at Santa Clara University in California. “You learn counting out change as a little kid -- if [the cashier] gives you a quarter too much, you give them back a quarter,” she says. “We have an ethical obligation to play fair and be honest.” You’d be quick enough to point out an error that cost you money, and the store or bank deserves that same consideration.

There could even be financial or legal repercussions for not doing your due diligence. For a bank error, “the bank can grab that money back at any time,” says Linda Sherry, a spokeswoman for Consumer Action, an advocacy group. That could overdraw your account or, with large spent sums, leave you subject to charges of theft.

Yes, reporting the windfall is to risk losing it, but not always. Businesses will sometimes leave the error in your favor. On vacation earlier this year, I used a $200 gift card to pay our group’s $90 restaurant bill. We returned the next night and racked up a bill of $120, but the server said the gift card fully covered our tab. Huh? We had $200 available on the card, he explained. I mentioned the previous night’s visit, and asked the restaurant to recheck. Nope, still $200. I spoke with the manager, who insisted the account was correct and any discrepancy was the restaurant’s problem, not mine. I left with an “extra” $80.

In cases where it becomes impossible to return the money (e.g., they won’t take it back or you notice it too late to rectify the problem), you can wash your hands of any guilt, McLean says. Lucky me.

We’re featuring valuable coupons and sales each Friday to help you spend less on the items you buy. Found a deal we missed -- or looking for a better price on a specific item? E-mail me at kgrant@smartmoney.com or send me a tweet @kellibgrant.

American Airlines. Here is a bit of strange marketing -- but why not take advantage? Up to four people traveling together can save 10% on an American international flight leaving from the U.S. with the airline’s new Century in the Making promotion. American AAdvantage members (membership is free) who pick five memorable football moments to vote for in the poll receive an e-mail promo code good for the discount. Participants don’t need to know anything about football -- there is no wrong answer. Purchases must be made on the American Airlines site for travel through May 31.

There are plenty of airfare sales out there, however, so make sure to check prices on a search engine like Kayak.com or BookingBuddy.com, which pull prices from airline and travel booking sites for comparison.

• Bing Travel

Gap, Banana Republic and Old Navy. During the Give and Get Event through March 21, save 30% on your in-store and online purchases at all three brands. (Five percent of your purchase goes to your choice of five nonprofits, including Feed America and Big Brothers Big Sisters.) Online, tack on up to two more coupon codes to further your savings: THANKYOU gets you $10 off and MYCARD gets you free shipping on orders of $100 or more. The catch: Both require you to use your store-brand credit card.

• See how your credit compares

Bloomingdale’s and Citibank. Through March 21, Citibank cardholders who use code CITI at checkout can save $25 on a purchase of $150 or more, and $50 on a purchase of $250 or more. Pair that with current store sales, which include 25% off DKNY and Calvin Klein intimates, 25% to 50% off designer shoes and 20% off kids’ purchases of $100 or more (increases to 30% on purchases of $200 or more).

Rita’s Italian Ice and Ben & Jerry's. On the first day of spring (this year, March 20) Rita’s franchises give away free regular-size Italian ices. Then on March 23, Ben & Jerry’s hosts its annual Free Cone Day with participating locations offering a free scoop to visitors between noon and 8 p.m.

Both events see a substantial turnout -- who doesn’t love free ice cream? -- so aim to get there early or be prepared to wait.

“New Moon.” Best Buy clearly hopes shoppers will line up to buy a two-disc DVD set of vampire film “New Moon” the same way they did for movie theater tickets. In a Black Friday-esque promotion, Best Buy is offering the set for $20 instead of $25 ($25 instead of $30 for Blu-ray) to customers who show up within two hours of store opening on March 20. “New Moon” standard packaging goes for $17 instead of $20 on DVDs, $22 instead of $25 for Blu-ray.

If you want to avoid the crowds, Amazon.com has those same door-buster prices as its regular preorder prices. Shipping is free on orders of $25 or more.

Related reading at SmartMoney:

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• Advice on spring cleaning services
• The best movie-rental options