I was one for two years at a Walmart and it was miserable to say the least. I honestly don't know how I lasted that long. There weren't many times where I messed up people's change but I dealt with plenty of rude customers. If you make one little mistake people demonize you for it as if you did it on purpose. I unintentionally pissed people off just with my awkward and bad social skills. As a quiet introvert with SA it is an exhausting job even without all of the bad experiences from customers. I really don't think it would have been as bad if I worked as a cashier at a smaller store like K mart or Albertsons where you're not dealing with a customer almost every second of the day.