Why don't you just do what I do: when you buy something in-person with cash and there's change, count the paper money and then just hastily count out the change

Why don't you just do what I do: when you buy something in-person with cash and there's change, count the paper money and then just hastily count out the change, knowingly giving more then the exact cent amount, and say "Keep the change, and no need for the receipt." Precious seconds can be saved every time. Also, if I'm in line behind someone who is taking too long with anything up to 2 dollars, I just say "I'll pay it" or I even quickly hand the cashier the money.