You are going to have to really concentrate on cutting back on eating the sweets. It is going to be very difficult for you because it's a habit that helps you get through your shift at work.
If you aren't allowed to take fruit, why are you allowed to have sweets in the kitchen?
I used to run restaurants and eating isn't allowed because you have to put your hand near your mouth - this applies to sweets aswell. If your boss allows sweets, why don't they allow grapes?
Anyway, it's only you that can do this, either allow yourself a set amount of syns, say 10 a day, just for sweets, or spend those syns after work on something that you really want.