Insurance agents licensed in this state may charge, receive and collect on the principal balance of unpaid insurance and bond premiums a time-price differential not to exceed the rate now provided for retail merchants under the Retail Installment Sales Act, compiled in title 47, chapter 11:
(1) On so much of the principal balance as does not exceed five hundred dollars ($500), ten dollars ($10.00) per one hundred dollars ($100) per year;
(2) If the principal balance exceeds five hundred dollars ($500), but is less than five thousand dollars ($5,000), eight dollars ($8.00) per one hundred dollars ($100) per year on that portion over five hundred dollars ($500); and
(3) If the principal balance exceeds five thousand dollars ($5,000), six dollars ($6.00) per one hundred dollars ($100) per year on that portion over five thousand dollars ($5,000).