Surcharge (I) Every dealer whose gross turnover during a year exceeds rupees five lakhs shall, in addition to the tax payable by him under this Part, also pay a surcharge at such rate not exceeding ten per centum of the total amount of the tax payable by him, as may be fixed by the State Government by a notification published in the official Gazette: Provided that the aggregate of the tax and surcharge payable under this Part shall not exceed, in respect of goods declared to be of special importance in inter State trade or commerce by section 14 of the central Sales Tax Act, 1256 (Act 74 of 1956), the rate fixed by section 15 of the said Act: The expression "gross turnover" as defined in section 2(j) Of the Act insofar as material reads: 148 "2(j) "gross turnover" means (i) for the purposes of levy of sales tax, aggregate of sale prices received and receivable by a dealer, during any given period, in respect of sale of goods (including the sale of goods made outside the State or in the course of inter State trade or commerce or export) but does not include sale prices of goods or class or classes or description of goods which have borne the incidence of purchase tax under section 4.