Would this be Stealing Money !?!?! HELP !?

My mom use to work at a convent store and then she quit to work at a better one because her old job was bad she did not like it but she is happy now ! But she made some really good friends there and whenever me or my dad/mom will go to buy something there a this one employ Ill call he jane ( not real name ) she takes like 10 or 20 $ off what we buy is this stealing and is it the costumers or employees fault thanks alot !