For the privilege of selling tangible personal property at retail, a tax is imposed upon all retailers at the rate of 2.25 percent of the gross receipts of any retailer from the sales of all tangible personal property sold at retail in Mineral County on or after July 1, 1971. (MC Ord. 89A §1, 1981: MC Ord. 85A §1, 1981: MC Ord. 40A §3, 1971: MC Ord. 39A §20, 1971)