(a) The sales and use tax does not apply to a sale to the State or a political subdivision of the State.

(b) The exemption under subsection (a) of this section may not be construed to exempt any sale of tangible personal property, a digital code, or a digital product, otherwise taxable under this title, to a contractor to be used under a contract with the State or a political subdivision of the State for construction, repair, or alteration of real property.