The original, or exact digital copy of the original, of all accounts, vouchers and documents approved or to be approved by the commissioner of administration shall be preserved in his office; and copies thereof shall be given without charge to any person, county, city, town, township and school or special road district interested therein, that may require the same for the purpose of being used as evidence in the trial of the cause, and like copies shall be furnished to any corporation or association requiring the same, under tender of the fees allowed by law; provided, that the commissioner of administration may destroy or dispose in the manner provided by law of all paid accounts, vouchers and duplicate receipts of the state treasurer and other documents which may have been on file in the office of the commissioner of administration or his predecessor as custodian of such documents for a period of five years or longer, except such documents as may at the time be the subject of litigation or dispute.