Notwithstanding other provisions of this chapter, when, in the opinion of the department, the nature of a taxpayers business renders it impracticable for the taxpayer to account for the sales or use taxes, as imposed by this chapter, at the time of purchase, the department may issue its certificate to the taxpayer authorizing the purchase at wholesale and the taxpayer is liable for the taxes imposed by this chapter with respect to the gross proceeds of sale, or sales price, of the property withdrawn, used or consumed by the taxpayer within this State.