What is 'taxable turnover ' was defined in subsection (2) of section 5 to mean : "that part of a dealer 's gross turnover during any period which remains after deducting therefrom (a) his turnover during that period on (i) the sale of goods declared tax free tinder section 6; (ii) sales to a registered dealer of goods of the class or classes specified in the certificate of registration of such dealer, as being intended for resale by him, or for use by him as raw materials in the manufacture of goods for sale; and of containers or other materials for the packing of goods of the class or classes so specified for sale : Provided that in the case of such sales a declaration duly filled up and signed by the registered dealer to whom the goods are sold and containing the prescribed particulars on a prescribed from obtainable from the prescribed authority is furnished in the prescribed manner by the dealer who sells the goods.