(1) The tax payable by a dealer for a year under the orissa Sales Tax Act, 1947 (hereinafter referred to as the said Act) shall be increased by an additional tax at the rate of C (a) two percent of the tax, if his gross turnover for that year does not exceed one lakh of rupees; (b) three percent of the tax, if his gross turnover for that year exceeds one lakh of rupees but does not exceed five lakhs of rupees; D (c) five percent of the tax, if his gross turnover for that year exceeds five lakhs of rupees Provided that where in respect of declared goods the tax payable by such dealer under the said Act together with the additional tax payable under this sub section exceeds the maximum percentage of the sale or purchase price thereof specified, from time to time, under clause (a) of section 15 of the , the rate of additional tax in respect of such goods shall be reduced to such an extent that the tax and the additional tax together shall not exceed such maximum percentage of the sale or purchase price of such goods.