31. Receipts from sales of tangible personal property and services taxable under any municipal ordinance which was adopted pursuant to P.L.1947, c.71 (C.40:48-8.15 et seq.) and was in effect on April 27, 1966 are exempt from the tax imposed under the Sales and Use Tax Act, subject to the following conditions:
a. To the extent that the tax that is or would be imposed under section 3 of P.L.1966, c.30 (C.54:32B-3) is greater than the tax imposed by such ordinance, such sales shall not be exempt under this section; and
b. Irrespective of the rate of tax imposed by such ordinance, such sales shall be exempt only to the extent that the rate of taxation imposed by the ordinance exceeds 6%, except that the combined rate of taxation imposed under the ordinance and under this section shall not exceed 13% on or before December 31, 2016, 12.875% on and after January 1, 2017 but before January 1, 2018, and 12.625% on and after January 1, 2018.