The amounts of compensation payable periodically under the law by agreement of the parties with the approval of the Nebraska Workers' Compensation Court may be commuted to one or more lump-sum payments, except compensation due for death, permanent disability, or claimed permanent disability which may be commuted only upon the order or decision of the compensation court pursuant to section 48-139; PROVIDED, that when commutation is agreed upon pursuant to this section or approved by order pursuant to section 48-139, the lump sum to be paid shall be fixed at an amount which will equal the total sum of the probable future payments, capitalized at their present value upon the basis of interest calculated at five percent per annum with annual rests. The fee of the clerk of the compensation court for filing, docketing, and indexing an agreement submitted for approval as provided in this section shall be fifteen dollars. The fees shall be remitted by the clerk to the State Treasurer for credit to the Compensation Court Cash Fund.