today you're a cashier....what will you be tomorrow?!

In your province, OP, it is against the Employment Standards Act for your employer to not provide you a half hour break for each period of work in excess of 5 hours, unless your union has agreed to something else, or there was an emergency in your workplace.

Your regional manager made a judgment based on a snapshot of your department. Yes, in a retail environment it looks awful to have employees sitting around doing nothing. Your RM probably also assumed that your management team obeys the law. You should inform your RM that they don't.