[Fey]

You're missing the point, what they're doing is in violation of Federal Law, so you need to tell HR. Not them, not that manager, it needs to go to the HR people. Walk in tomorrow, go back to the break room, take down the number. Ask your shift leader/manager what time your first break it. On that break step outside and call HR. List what's going on.

It doesn't matter what they say, what they're doing is against the US government law, and against most states labor laws.

however, I can talk myself blue in the face, you have to decide to do something about it. And if you don't, well, they'll keep doing this to you.