Question about not getting paid over time?

I work at a resturaunt as a bus boy. The owner always does alot of things that i know she cant..but one thing im not sure about is sometimes I work late...my shift would be from 5-9...but sometimes i get out at 10:30 because im cleaning up/finishing up because im the only bus boy. but she doesnt pay me the extra hours. she just pays me the 5-9. i dont really want to tell her anything since she has a fit for everything.. and i dont want to just leave when my shift is over because shell have a fit the next day if i didnt finish something... however, friends and family tell me she cant do this and should be paying me the ful time im there workin. but im not sure since shes the owner, if this is legal. can anyone help me out? should i speak up?