For the privilege of selling tangible personal property at retail, a tax is hereby imposed upon all retailers in the city at the rate set forth in CMC 3.24.020 of the gross receipts of the retailer from the sale of all tangible personal property sold at retail in the city on and after the operative date of this chapter (January 1, 1974). (Ord. 173 § 1. 2002 Code § 7-1.6).