I work at Subway.. 8 hour shift.. NO breaks.....?

I work at Subway and from the moment I walk in until my shift is over, I'm not allowed to stop working for five seconds. We have plenty of people that work at my Subway but my boss only puts two people on a shift at one time.. is it right for him to not let us have a 2 minute smoke break at all? I'm not asking for a 15 minute break.. I would just like to be able to step outside when there are no customers and every thing has been done and just smoke a cig real quick every three or four hours.. but my friend at work said you have to sneak and that's what he does. Should I ask my boss if it's okay or just keep sneaking every 3 hours?