Clerks can't count. Last cash purchase was for like $4.40. Handed a $20. She rang it up as a $10, she realized her mistake, got confused, called over her manager (yeah, I was watching along for sport at this point), told her what she had done, and wasn't sure how to proceed (the sane people thinking, just grab what the register told her and a $10, easy right), nope, manager prints the receipt, grabs a calculator out of the cabinet (barely holding in the laughter by now), punches it all in, and then explains to the cashier how to count it out from the drawer. Priceless.