There is imposed on any person engaging in business in this municipality for the privilege of engaging in business in this municipality an excise tax equal to three eighths of one percent (.375%) of the gross receipts reported or required to be reported by the person pursuant to the New Mexico Gross Receipts and Compensating Tax Act as it now exists or as it may be amended. The tax imposed under this section is pursuant to the Municipal Local Option Gross Receipts Taxes Act as it now exists or as it may be amended and shall be known as the "municipal hold harmless gross receipts tax."