The employer should pay the employee, the idea that customers should be charged more than the advertised price (false advertising) or expected to pay more because the employer is a tightwad is ridiculous.
Customers pay for it one way or the other. If the employer pays more, they have to charge more for the food. With a tip you decide how much the service was worth, and the server has a motivation to provide good service. As for false advertising, that’s ridiculous. You know going in that it’s customary to add another 15% or so to a sit down dinner. You are just rationalizing your stinginess.