The Laboratorium

Here's the sequence of events. First, I gave the guy behind the counter the book, which was marked as $12. He punched some stuff into the register, turned back to me, and said "$9.77." I gave him a twenty. He punched some more stuff into the register, which then read $190.13. He opened the drawer and gave me eleven dollars and thirteen cents in change. End of transaction. I guess you can't get the most dedicated of staff for the all-night shift.