(1) Upon every person, firm, or corporation, (including the State of Alabama, the University of Alabama, Auburn University, and all other institutions of higher learning in the state, whether such institutions be denominational, state, county, or municipal institutions, and any association or other agency or instrumentality of such institutions) engaged, or continuing within the county in the business of selling at retail any tangible personal property whatsoever, including merchandise and commodities of every kind and character, (not including, however, bonds or other evidences of debts or stocks, nor sales of material and supplies to any person for use in fulfilling a contract for the painting, repair, or reconditioning of vessels, barges, ships, and other watercraft, and commercial fishing vessels of over five tons displacement as registered with the United States Coast Guard and licensed by the State of Alabama Department of Conservation and Natural Resources), an amount equal to one percent of the gross proceeds of sales of the business except where a different amount is expressly provided herein. Provided, however, that any person engaging or continuing in business as a retailer and wholesaler or jobber shall pay the tax required on the gross proceeds of retail sales of the business at the rates specified, when his or her books are kept so as to show separately the gross proceeds of sales of each business, and when his or her books are not so kept he or she shall pay the tax as retailer on the gross sales of the business. Where any used part including tires of an automotive vehicle or a truck trailer, semitrailer, or house trailer is taken in trade, or in a series of trades, as a credit or part payment on the sale of a new or rebuilt part or tire, the tax levied herein shall be paid on the net difference, that is, the price of the new or used part or tire sold less the credit for the used part or tire taken in trade, provided, however, this provision shall not be construed to include batteries.
(6) Upon every person, firm, or corporation engaged or continuing within the county in the business of selling at retail any machine, machinery, or equipment which is used in planting, cultivating, and harvesting farm products, or used in connection with the production of agricultural produce or products, livestock or poultry on farms, and the parts of such machines, machinery, or equipment, attachments and replacements therefor which are made or manufactured for use on or in the operation of such machine, machinery, or equipment, and which are necessary to and customarily used in the operation of such machine, machinery, or equipment, an amount equal to one-half percent of the gross proceeds of the sale thereof; provided, that the one-half percent rate herein prescribed with respect to parts, attachments, and replacements shall not apply to any automotive vehicle or trailer designed primarily for public highway use, except farm trailers used primarily in the production and harvesting of agricultural commodities. Where any used machine, machinery, or equipment which is used in planting, cultivating, and harvesting farm products, or used in connection with the production of agricultural produce or products, livestock, and poultry on farms is taken in trade or in a series of trades as a credit or part payment on a sale of a new or used machine, machinery, or equipment, the tax levied herein shall be paid on the net difference, that is, the price of the new or used machine, machinery, or equipment sold, less the credit for the used machine, machinery, or equipment taken in trade.