There is hereby levied a statewide privilege tax upon every person, firm, corporation, or association, other than banks, state or national, doing business of lending money secured by mortgages, trust receipts, retained-title or purchase contracts, on motor vehicles, furniture, refrigerators containing mechanical freezing units operated by gas or electricity, or radios or any other tangible personal property, located in the State of Mississippi, or doing a business of purchasing, discounting, or otherwise acquiring notes, trust receipts, or other forms of indebtedness secured by liens, in the form of mortgages, retained-title or purchase contracts, or other liens, upon motor vehicles, furniture, refrigerators containing mechanical units operated by gas or electricity or other fuels, or radios or any other tangible personal property, located in this state (not including, however, cotton, cotton seed or agricultural products); the amount of said tax to bear a direct relationship to the value of the securities held, owned, or acquired by such person, firm, corporation or association, and exacted in return for the protection afforded by the government and laws of this state in the enjoyment of such ownership and rights acquired thereby; the tax to be computed by application of the rate hereinafter set out to the total value of such securities, other than those securities representing loans for the payment of the wholesale sales price and those securities representing transactions known as "floor plan," upon which no tax is to be imposed. Provided, however, that the tax imposed in this chapter shall not apply to (a) persons, firms or corporations engaged in the general mercantile business, who make advancements of money, merchandise and supplies to their customers and who take mortgages, deeds of trust or other liens upon personal property to secure the payment of the indebtedness thus incurred; or (b) a member of an affiliated group as defined by Section 1504 of the Internal Revenue Code of 1986, as amended, on July 1, 1995, with respect to loans made by one member of the affiliated group to another and who is not otherwise engaged in the business of loaning money secured by tangible personal property.