A childhood belief about going shopping

When I was younger, probably to young to go into the drugstore by myself even in our small town, My mother would often charge her medicine. She would drop me off at the door, I guess the drugist knew what I wanted because something had been called in, and tell me to charge it. I would often get charge and cash mixed up. So when he said will this be cash or charge, I would say cash, and then we both would just stand and wait, he waited for cash and I waited for him to say O.K. or thank you so I would feel as if I could leave. I would say charge to myself all the way in to the store but once he said, cash or charge, the confusion set in.