Notwithstanding the provisions of the first paragraph of clause seventeenth D of section 5 of chapter 59 of the General Laws or any other general or special law to the contrary, the town of Tewksbury may grant an exemption pursuant to said clause seventeenth D in the amount of $500; provided, however, that the town of Tewksbury may decrease the minimum age of eligibility for such an exemption from the age of seventy to the age of sixty-five; provided, further, that the town may increase the whole estate limit, real and personal, for such an exemption from forty thousand dollars to fifty-five thousand dollars; provided, further, that following the enactment of this act, the Tewksbury board of selectmen may vote annually to increase such exemption to an amount in excess of $500 and increase the whole estate limit, real and personal, in excess of fifty-five thousand dollars; provided, further, that such vote shall not increase the exemption amount or the whole estate limit by more than 5% annually relative to the most recent amount or limit established in the preceding year; and provided further, that the provisions of the second paragraph of said clause seventeenth D shall apply mutatis mutandis to this act.