There are exempted from the computation of the amount of the sales tax the gross receipts from the sale of any tangible personal property to:
1. The United States, its unincorporated agencies and instrumentalities.
2. Any incorporated agency or instrumentality of the United States wholly owned by the United States or by a corporation wholly owned by the United States.
3. The State of Nevada, its unincorporated agencies and instrumentalities.
4. Any county, city, district or other political subdivision of this State.
(Added to NRS by 1967, 905; A 1995, 1440)