Commencing October 1, 1996, any pensioner who retired from a city, town, county, or public or quasi-public organization of the state before the city, town, county, or public or quasi-public organization of the state became a member of the Employees’ Retirement System, and who is receiving a monthly benefit prior to October 1, 1996 administered by the Employees’ Retirement System, may receive an increase in benefits in the amount of thirty dollars ($30) per month if the monthly benefit is five hundred dollars ($500) or less; forty-five dollars ($45) per month if the monthly benefit is more than five hundred dollars ($500) but less than one thousand dollars ($1,000); sixty dollars ($60) per month if the monthly benefit is more than one thousand dollars ($1,000) but less than two thousand dollars ($2,000); seventy-five dollars ($75) per month if the monthly benefit is two thousand dollars ($2,000) or more if the city, town, county, or public or quasi-public organization of the state elects to fund the increase, provided the pensioner retired prior to October 1, 1996.