There is imposed an excise tax at the rate of five percent on the purchase price of any aircraft purchased or acquired either in or outside of the state of North Dakota or on the lease or rental cost of any aircraft, less fuel, if rented dry and required to be registered under the laws of this state, except on aircraft or helicopters designed or modified for exclusive use as agricultural aircraft for aerial application of agricultural chemicals, insecticides, fungicides, growth regulators, pesticides, dusts, fertilizer, or other agricultural materials, the excise tax is imposed at the rate of three percent on the purchase price of any such aircraft purchased or acquired in or outside of this state, including the leasing or renting of such agricultural aircraft to users for agricultural purposes.