If for any reason the tax is not paid when due, interest at the rate of six percent (6%) per annum on the amount of such tax, and an additional penalty of one-half of one percent (.5%) of the amount of the unpaid tax for each month or fraction thereof during which the tax remains unpaid, shall be added and collected. Where suit is brought for the recovery of any such tax, the person liable therefore shall, in addition, be liable for the costs of collection and the interest and penalties herein imposed. (Ord. 940. Passed 11-28-66.)