(a) Gratuities to employees are the property of the employees, and employers shall not keep gratuities. Failure to pay gratuities owed to an employee more than 13 days after the end of the pay period in which such gratuities were earned constitutes a violation of this Act.
     (b) This Section does not prohibit an employer from withholding from gratuities paid by credit card a proportionate amount of any credit card processing fees that the employer must pay in connection with the transaction, provided that the amount withheld does not exceed the proportion of the amount of the tip to the amount of the overall bill, regardless of whether the overall bill was paid using a credit card. This Section does not prohibit tip pooling as permitted by law. This Section does not affect an employer’s entitlement to an allowance for gratuities to the extent permitted under subsection (c) of Section 4 of the Minimum Wage Law.