I can think of a couple. I bought a few things at Wal-Mart, including a pair of work shoes that were $39.99. It rang up to less than $25.00. I knew that couldn't be right, and said so. The clerk hadn't scanned the shoes. She corrected it, and I paid it. I have been given incorrect change in my favor several times, and I've always pointed it out. I'm also quick to point out when they overcharge me. I recently had a cake scan the higher and the wrong price in the self-serve check out at Albertson's. I had to get a clerk to help since the cake was on sale. She insisted on giving it to me for free, I said I didn't mind paying the correct price, but she said it was store policy, so I took it. That's just me, but I can't speak for others.
Cheri