Authorized agents may retain fifty cents out of the money collected by them on each transaction in which specific ownership tax is collected, which fifty cents is the only remuneration an authorized agent is allowed to retain for collecting specific ownership taxes and issuing receipts. In counties of the fifth class, the authorized agent shall use the retained funds to defray the necessary expenses in connection with the collection and administration of specific ownership taxes as directed by articles 1 to 4 of this title 42. Authorized agents in all other counties above the fifth class shall deposit in the general fund of said city and county, or of said county, all such sums so retained under this section.