Most of these can apply to any retail situation, tbh.
But 21 bugs the hell out of me. Why get so pissy over something like that? In some cultures, it’s customary to put ALL cash in a little tray on the counter for the cashier to collect (and likewise for you to collect your change). Don’t get all upset over something like that, especially if the person you’re serving is foreign because hey, that’s probably what they know to be appropriate.