Where documents of evidence with respect to purchases are not obtained or kept by a profit-seeking enterprise or are found to be incorrect upon verification, the collection authority-in-charge may determine the purchase costs on the basis of the lowest prices prevailing in the year at the locality concerned.
Where documents of evidence with respect to sales are not issued to others or the counterfoils thereof are not kept by a profit-seeking enterprise, the collection authority-in-charge may determine the selling prices on the basis of the highest prevailing in the year at the locality concerned.