As a cashier myself, this is so true. I say no problem all the time, and no one else has a problem. You sound just as nice when you say "no problem" vs. "youre welcome" ; Agreed, I say "No problem" to people all the time.
starting conversations <<< I have a friend (more like aquaintance) that sends a text asking "what are you doing" and then she replies to all of my texts with answers. She doesn't try to keep conversation going and it annoys me endlessly.