Check your receipts when walking out of the grocery store. I guess a better lesson would be making sure you pick up the right item in the first place, but lets not quibble.
I'm babysitting overnight for the rest of the week, leaving Gameboy home by himself. I haven't been to the grocery store in a while and needed to grab a few things to get him through the week. Usually I look at all the ads, maybe go to two stores, Coupons are arranged in the envelope with a list written on the back. There wasn't time for any of that today. I headed to the store closest to the other errands that needed taking care of and grabbed his staples- cheese, milk, cereal, and bananas. In the process I learned that his favorite cereal was on sale for 1.88. I decided to grab a box and see if I could find any coupons online at home*.
After 10 minutes of searching online I gave up and carried on with the rest of my to do list for the day. A few more errands and I was back at the store to buy cereal in bulk**. I picked up what will hopefully be 2 months worth for him and two boxes for me. I check out, happy with the amount of food I'm getting for the money. I also had a great checker who applied the print out coupons to my current bill.
Something told me to check the bill as I walked out. My cereal, which should have started at 2/$4 rang up at $3.19. By this point I was at the car and almost went home. I knew it wouldn't get done later this week so I went back in with the boxes in question. A manager I recognized was checking up front, so I asked if I could leave my bags with her*** and get the correct boxes. She said that was fine so I went and grabbed the slightly bigger boxes that were actually on sale. She rang things up and then gave me the change (2.38) in cash****.
I know a lot of people who would say it wasn't worth the time to go back in, but considering it took around 8 minute it works out to $17.85 an hour. For me that's worth it.
So the many morals of the story:
-Try to pick up the right items in the first place
-Check your receipt before you make it home
-If you'll save more than a few cents take the time to go back in and get errors (yours or theirs) adjusted.
*This particular store is 4 blocks from my house and I knew I'd be driving by later today. The same store is also across from the babysitting house, so if anything I could have gotten them tomorrow.
** Gameboy eats the same cereal every day
*** The service desk was closed
****This is now sitting in the change jar for the bimonthly deposit.