It sounds to me as he has trouble dealing in fractions and got very defensive when it was pointed out to him. I think I would just take my receipt back in and ask to speak to the owner or manager. Explain it very calmly as you did here and tell the owner/manager that at first you were just going to 'eat' the $6 but the more you think about it, you feel it does need to be brought to the attention of someone. I think you will feel better after you do that, even if an adjustment isn't made. I hope this is not a repeat of other posts...I have only read your initial posting and I don't have the time right now to read the others...I need to be on my way to an appt.