Each person engaged in buying, selling or renting real estate on commission, when such real estate is situated in this state, shall pay to the state the following license tax: In cities and towns of 10,000 inhabitants and over, $15; in cities and towns of less than 10,000 and more than 5,000 inhabitants, $10; and in all other places, $5.
Ala. Code § 40-12-149 (1975)