Every dealer liable to pay surcharge under section 16 shall, in addition to the surcharge payable by him, by liable to pay an additional surcharge at the rate of five per centum of the total amount of tax payable by him under section 17 and section 21;

Provided that notwithstanding any surcharge payable under section 16, no additional surcharge shall be payable by a dealer on the tax payable on that part of his taxable turnover of sales as represents –

(a) sales referred to in sub-section (2) of section 17 ;

(b) sales of such goods or such class of goods as the State Government may, by notification, specify ;