While transacting his business, a transient vendor shall post in a prominent place, so that they may clearly be seen by purchasers of the merchandise or services which he is offering, his state sales tax number, his transient vendor license number, and a statement that he is required to give purchasers, at the time of payment, receipts for purchases that include sales tax. The postings required in this section shall be written in bold, legible letters and numbers not less than one (1) inch in height. The transient vendor shall keep a running total of his sales.