In this Act, unless the subject or context otherwise requires,-

(36) "sale price" means the amount paid or payable to a dealer as consideration for the sale of any goods less any sum allowed by way of any kind of discount or rebate according to the practice normally prevailing in the trade, but inclusive of any statutory levy or any sum charged for anything done by the dealer in respect of the goods or services rendered at the time of or before the delivery thereof, except the tax imposed under this Act;

Explanation I.- In the case of a sale by hire purchase agreement, the prevailing market price of the goods on the date on which such goods are delivered to the buyer under such agreement, shall be deemed to be the sale price of such goods;

Explanation II.- Cash or trade discount at the time of sale as evident from the invoice shall be excluded from the sale price but any ex post facto grant of discounts or incentives or rebates or rewards and the like shall not be excluded;

Explanation III.- Where according to the terms of a contract, the cost of freight and other expenses in respect of the transportation of goods are incurred by the dealer for or on behalf of the buyer, such cost of freight and other expenses shall not be included in the sale price, if charged separately in the invoice;

Explanation IV.- The amount received or receivable by oil companies for the sale of diesel and petrol to the retail outlets in the State shall be deemed to be equivalent to the price on which the retail outlets sell these commodities to the consumer;