Is there an overt contradiction between ' Most menu prices include taxes and a service charge, but it's customary to leave a tip if you were served satisfactorily.' and 'Tips are not accepted at most restaurants, as there is already a sales tax.'
 Most menu prices include taxes and a service charge, but it's customary to leave a tip if you were served satisfactorily.###Tips are not accepted at most restaurants, as there is already a sales tax.