Should a restaurant subtract tip share from tips made or total sales?

i am a waiter at a restaurant and the restaurant subtracts a percent to give to the buss boy, servers, bartender, etc... but they don't take the percentage from my tips they take it from the money that was made from the food sales from me, for example if for one day i made 200$ in tips and the money the restaurant made in food sales from me was 1500$ they take 7% from 1500$ instead of 7% from the 200$ the money i actually made, so i would have to pay 105 dollars from the 200 dollars i made instead of 14 dollars, i was wondering if this was legal