I always worry about getting the clerk in trouble. WE are all new at sometime and make beginner mistakes. I also go through my life exhausted most of the time and i seldom notice their mistakes or my mistakes, seldom even see the ringing out...most the time it is a second to close my eyes and try to breathe. I am grateful when a clerk is honest and hands me back if i hand them too much money. IT happens. I Doubt i would notice if they didnt'.