In a wholesale sale of cigarettes, the presumptive wholesale markup of 5 percent provided for in § 11-501(e) of this subtitle may be reduced by 2 cents for each carton of 200 cigarettes, if: The cigarettes are not delivered unless their full price is received by the wholesaler at or before delivery; and The purchaser performs or pays for the cartage cost of the cigarettes to the place of business of the purchaser. In the absence of satisfactory proof of a lesser aggregate cost of doing business, a vending machine operator or retailer who purchases cigarettes at prices ordinarily invoiced to a wholesaler and who receives the wholesaler’s discounts on them shall: First, add to his basic cost of cigarettes the wholesale markup of 5 percent provided for in § 11-501(e) of this subtitle to cover the cost of doing business as a wholesaler; and Then, on the resultant sum, add the retail markup of 8 percent provided for in § 11-501(d) of this subtitle. If the discount received by the vending machine operator or retailer is less than that ordinarily allowed to wholesalers, the wholesale markup of 5 percent may be reduced by the difference between the discount ordinarily allowed to wholesalers and the discount received by the retailer or vending machine operator. A wholesaler who sells cigarettes to another wholesaler or to a vending machine operator is not required to include in his selling price the cost to the wholesaler. However, in the absence of satisfactory proof of a lesser cost for the service rendered, the wholesaler shall include in the selling price his basic cost of cigarettes, plus a charge of 1 percent of his basic cost of cigarettes. If a wholesaler purchases cigarettes from another wholesaler, then, on resale of the cigarettes to a retailer, he is the wholesaler for the purposes of this subtitle.