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:
A. The United States, its unincorporated agencies and instrumentalities;
B. 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;
C. The state of Nevada, its unincorporated agencies and instrumentalities;
D. Any county, city, district or other political subdivision of the state of Nevada;
E. Any organization created for religious, charitable or eleemosynary purposes; provided, that no part of the net earnings of any such organization inures to the benefit of any private shareholder or person. (MC Ord. 39A §64, 1971)