Every multistate taxpayer as defined in said Compact and required to file a return in Idaho whose only activities within Idaho consist of sales and which does not own or rent real estate or tangible personal property and whose dollar volume of gross sales made during the tax year within this state is not in excess of the dollar volume prescribed in article III, section 2, of the Multistate Tax Compact may elect to report its income and pay tax to the state of Idaho at the rate of one per cent (1%) of such dollar volume.