I hate my customers!?

i am going to go insane. my customers are so greedy and annoying. i work in a department store where who ever walks in i have to say welcome and ask how are you? (and honestly i dont give a **** how you are) sometimes when im ringing some one out i say how are you, no response. reciept in the bag? they just stare at me like im some idiot and dont say anything so i shove in the bag and just walk away before i scream!!!!!!!!!!!!!!!! honestly working there has made me a mean person and i am a VERY nice person when im not working . my first customer i had ever had told me i was stupid and didnt know what i was doing and said she wanted some one with more experience and this was after i told her her coupon expired! but that *** got what she wanted after a manager suckled her *** crack. and dont get me started on the fitting rooms they are ridiculous, people have no respect for our clothes aand think the ociates are slaves and they are the kings and queens. and my pay isnt even that good one payday i got 80 dollars because they only gave me 2 five hour days in 2 weeks. should i just quit my job? and what are some good tips so i dont go insaneeeee!!!!!!