Each dealer shall add the amount of the tax imposed under this article, as far as practicable, to the sale price or charge. The tax shall be a debt from the purchaser or consumer to the dealer until it is paid and shall be recoverable at law in the same manner as authorized for the recovery of other debts. Any dealer who neglects, fails, or refuses to collect the tax provided for in this article upon a retail sale of tangible personal property made by him, his agent, or his employee when the sale is subject to the tax shall be liable for and shall pay the tax himself.