A member upon retirement for service shall receive a monthly retirement allowance computed according to his or her completed creditable service credit years of service as follows: Five years but under ten years, one-twelfth of one percent of his or her final average salary for each month of service; ten years but under twenty years, one-twelfth of one and one-half percent of his or her final average salary for each month of service; and twenty years and over one-twelfth of two percent of his or her final average salary for each month of service: PROVIDED, That the recipient of a retirement allowance who shall return to service as a law enforcement officer or firefighter shall be considered to have terminated his or her retirement status and he or she shall immediately become a member of the retirement system with the status of membership he or she had as of the date of retirement. Retirement benefits shall be suspended during the period of his or her return to service and he or she shall make contributions and receive service credit. Such a member shall have the right to again retire at any time and his or her retirement allowance shall be recomputed, and paid, based upon additional service rendered and any change in final average salary.