Is there a reporting pay law in Minnesota?

I run a pizza place in Minneapolis, and I was told by my boss that I had to schedule employees for at least 2 hours but could send them home before their full shift was completed if we weren't busy. Someone that works for me told me that they had heard people had to be paid for at least 3 hours if they came to work. I can't find any information on this except that it is referred to as a reporting pay law. Does anyone know if this is a law in Minnesota? Also, is it correct that people can be scheduled for only 2 hours?