I bought a couple office phones and an office chair at an office supply store about ten or fifteen years ago. Each item was between $60-$90, and I had several other lower priced items as well.
I don’t recall the exact details, but I remember that the checker rung it up incorrectly. It was in my favor, but being the nice person I am, I pointed out her error. She looked it over, and said there was no error. I said “yes, there is, you charged me the wrong price for <item x>” or whatever it was that was wrong. It was a difference of about $50 if I remember correctly.
At that point, she started arguing with me. I didn’t think it was worth it to argue with her, so I gladly took the items and left.