The ordinary expenses of Mill Group Boards and their subsidiary bodies shall be financed locally in such a manner as may be agreed upon by the growers and the mills concerned, save that in respect of the costs and expenses of cane testing, clause 157 shall apply in respect of the apportionment of such costs between growers and the mill. A Mill Group Board may impose levies to provide for such expenses and, insofar as such levies are imposed on growers, direct the relative mill to deduct the levies from cane payments which become payable by the mill to the growers concerned. The extraordinary expenses of Mill Group Boards incurred at the instance of the South African Sugar Association or the Administration Board shall be paid by the South African Sugar Association at such rates as may be determined by the South African Sugar Association from time to time.