The tax payable under section 5 and section 5A shall be increased by an additional sales tax at the rate of-

(i) one rupee per litre on High Speed Diesel Oil, Petrol falling under sub-entries (ii) and (iv) of serial number 1 of the Schedule, and

(ii) fifteen per cent of the tax payable under the said sections with respect to other commodities:

Provided that no additional sales tax under this section shall be levied on the tax payable on Foreign Liquor falling under serial number 2 of the Schedule:

Provided further that the Government may, by notification in the Official Gazette, vary the rate specified in item (i) above.