The resolution authorizing the refunding bonds may provide that in addition to all other amounts to be paid into a sinking fund for such bonds, such sums shall be levied, assessed and collected for such sinking funds as bear a stated proportion of taxes of any kind which are imposed or collected for all purposes other than the payment of refunding bonds issued pursuant to this chapter, so that for every dollar of tax imposed or collected for all such purposes a stated amount shall be imposed for the said sinking fund.