318.6 Gratuities.

An amount or percentage, regardless of its designation, added to the price of meals pursuant to a requirement of the retailer furnishing such meals is a part of the sales price of such meals and must be included in the measure of the tax even though all or a part thereof may be paid by the retailer to his employees. Conversely, when a customer voluntarily provides a tip for an employee of a retailer, such a tip is not subject to the sales tax whether given directly to the employee in cash or added by the customer to his bill and charged by the retailer to the customer’s account; provided, however, that in the latter instance the full amount of such tip is turned over to the employee by the retailer.