I work for a high street retailer and my hours of work are 9 - 5.30. The store closes at 5.30 and after the store has closed I have to stay back to put the takings in the till. This usually takes till 5.40ish however if there's customers still in the shop it can take till 5.50ish. I'm only paid until 5.30 and my manager will not give me the time back. If I am late the next day because of traffic I am told to take time off my lunch even though I have worked 20 minutes over the night before.
Is my employer allowed to do this?