The accounting officers are hereby authorized to allow, hereafter, such commissions as they shall deem reasonable for the collection of moneys due from public defaulters and their sureties, not exceeding five per cent. upon sums under one thousand dollars; four per cent. upon sums of one thousand dollars and not exceeding two thousand dollars; and upon all sums above that amount not exceeding three per cent.
72 P.S. § 4229