Section 56:7-21 - "Cost to the retailer" defineda. The term "cost to the retailer" shall mean the "basic cost of cigarettes" to the retailer plus the "cost of doing business by the retailer," as evidenced by the standards and methods of accounting regularly employed by him in his allocation of overhead costs and expenses, paid or incurred, and must include, without limitation, labor (including salaries of executives and officers), rent, depreciation, selling costs, maintenance of equipment, delivery costs, all types of licenses, taxes, insurance and advertising; provided, that any retailer who, in connection with the retailer's purchase, receives not only the discounts ordinarily allowed upon purchases by a retailer but also, in whole or in part, discounts ordinarily allowed upon purchases by a wholesaler shall, in determining "cost to the retailer," pursuant to this subsection, add the "cost of doing business by the wholesaler," as defined in section five of this act, to the "basic cost of cigarettes" to said retailer, as well as the "cost of doing business by the retailer."b. In the absence of the filing with the director of satisfactory proof of a lesser or higher cost of doing business by the retailer making the sale, the "cost of doing business by the retailer" shall be presumed to be eight per centum (8%) of the "basic cost of cigarettes" to the retailer.c. In the absence of the filing with the director of satisfactory proof of a lesser or higher cost of doing business, the "cost of doing business by the retailer," who, in connection with the retailer's purchase, receives not only the discounts ordinarily allowed upon purchases by a retailer but also, in whole or in part, the discounts ordinarily allowed upon purchases by a wholesaler, shall be presumed to be eight per centum (8%) of the sum of the "basic cost of cigarettes" and the "cost of doing business by the wholesaler."L.1952, c.247, p.825, s.4.