"In my current position I have been trained to avoid this situation entirely by leaving the cash visible (out of the till and on the counter close to me) until I have provided the customer with their correct change. I will also confirm with the customer the bill type they have given me. For instance; if they hand me a 20 bill, I will say out loud 'here is your 10 dollars back from twenty?'. They will then say 'yes' - confirming that we are both on the same page. These methods help me to ensure that I am always giving back the correct change and that there are is no confusion between me and the customer."
