This one was an everyday occurrence.
It usually went something like this - cashier puts in the code for some produce (we use codes because we don't have scanners, obviously we're not charging $21.02 for a package of brussel sprouts)
Customer freaks out, "omg how is that $21.02?"
"No ma'am that's just the code for it, if you notice after I type in the code the actual price comes up."
2 minutes later, "why are you charging me 11.60 per pound of potatoes!!!"
"No, that's just the code." Customer grabs receipt, holds up the line and meticulously reviews every item, re-weighing the produce to make sure a young adult old isn't cheating them out of their money.
- Shocked and Awed