As used in this part, unless the context otherwise requires:
(1) “Commissioner” means the commissioner of revenue;
(2) “Department” means the department of revenue;
(3) “Gross receipts,” for the purpose of taxes administered under this part, means total receipts before anything is deducted, but does not include receipts from incidental business, when such incidental business, if separately carried on, would not be subject to a tax measured by gross receipts under parts 2-6 of this chapter;
(4) “Gross receipts” does not include state and local sales and other taxes collected from customers and remitted to the respective taxing authorities by utilities; and
(5) “Incidental business” means a business carried on separately and not a part of the business made the subject of privilege taxation.