A county transportation use tax imposed pursuant to this article shall be paid to the Tax Commissioner by the user of tangible personal property or custom software or the results of a taxable service in the county that imposes the county transportation use tax, unless the county's use tax is collected by a retailer located outside the county that is a retailer engaging in business in the county as defined in this article, or the retailer is an out-of-state retailer who is required to collect West Virginia state and local use taxes.