The retailer shall add the tax imposed by this chapter to the sale price or charge, and when added the tax constitutes a part of the price or charge, is a debt from the consumer or user to the retailer, and is recoverable at law in the same manner as other debts; provided, that the amount of tax that the retailer collects from the consumer or user is as follows:
and where the amount of the sale is more than one dollar and eight cents ($1.08) the amount of the tax is computed at the rate of six percent (6%); provided, that the amount of tax that the retailer collects from the consumer or user for the period commencing July 1, 1990 is as follows:
and where the amount of the sale is more than one dollar and seven cents ($1.07) the amount of the tax is computed at the rate of seven percent (7%).