A long time ago I worked part-time in a dining hall, with an actual time clock. They told me to clock in at 4:45 p.m. After several paychecks it seemed to me that even with taxes and union dues I was making a bit less than I should. The paychecks were very hard to read, but finally I figured out that they were cheating me of 15 minutes a shift. I asked the manager, who said that I wasn't supposed to clock in till 5. And of course she never told me till I asked -- she was perfectly happy to have me working 15 minutes a day for free. And I was too young and cowed to complain to anyone (union or higher up or whoever).