Where any goods are chargeable to duty on the basis of retail price under this Act and the retail price is not indicated on the goods in the manner specified therein or in the rules made there under, the duty shall be charged at the rate of 500 per cent ad valorem in case of cigarettes, and 40 per cent ad valorem in case of goods other than cigarettes.

Provided that in cases where a registered person does not intend to print retail price for any genuine reasons, he may voluntarily pay duty on the said higher rates as applicable to him and declare his duty payments in the return accordingly and other provisions of this section shall not apply in such cases.