I like to pay with cash. I like the anonymity of it. I calculate my change due mentally. They don't count it back anymore

If you're buying multiples of an item, a lot of cashiers scan the item, set it down on the belt side of the register, type in the number purchased and then slide the item over the reader, scanning it again. I catch a few a year doing that. I caught a cashier doing that at Aldi today. When possible, I always try to keep an eye on the scanning process and immediately point out mistakes. Even though I watch, we always check our receipts and a little over 20% have extra items on them, where something was scanned more than once. The cashiers slip a lot through when you are putting groceries on the belt or bagging. I don't think it's intentional, just incompetence

Keith