The township board of any township, when requested by the treasurer, may authorize the transfer of interest earned on any of the moneys of the township into the fund of the township that is most in need of the interest. This Section does not apply to any interest earned that has been earmarked or restricted for a designated purpose. This Section does not apply to any interest earned on any funds for the purpose of municipal retirement under the Illinois Pension Code and tort immunity under the Local Governmental and Governmental Employees Tort Immunity Act. Interest earned on these funds may be used only for the purposes authorized for the respective funds from which the interest earnings were derived.