(1) The librarians, assistants and employees of any public library may, at the discretion of the board of directors of the library, be included within and participate in the pension, retirement, sickness, disability and death benefit system established under Section 10-3-1103. In the event the librarian, assistants and employees of the municipality are included within and participate in the system, there shall be deducted from the monthly wage or salary of the librarian, assistants and employees and paid into the system, a percentage of their wage or salary equal to the percentage of the monthly wage or salary of other employees of the municipality which is paid into the system. Also there shall be paid monthly into the system from the funds of the library a further sum equal to the total amount deducted monthly from the wage or salary of the librarian, assistants and employees and paid into the retirement system.

(2) Where the election by the board of directors of any library for inclusion of its librarian, assistants and employees within the system of any municipality is subsequent to the establishment of the system, the inclusion may begin as of the date of the establishment of the system or as of the date of the election as shall be determined by the board of directors. If inclusion is as of the date of the establishment of the system, there shall be paid into the system in addition to the subsequent monthly wage deductions and matching sums, a sum equal to the aggregate of monthly payroll deductions and matching sums that would have accrued during the period beginning with the establishment of the system and ending with the election had the librarian, assistants and employees been included within the system from its establishment.