If in the determination of any tax rate a fraction of a cent occurs, the board may adopt a rate ending in the next higher tenth of one cent ($0.001). An excess over the amount specified in the budget, arising from the use of the tenth of one cent tax rate, is not a violation of this chapter. Any cash collected resulting from such excess or from an excess resulting from any other cause shall not invalidate the levies but shall be applied in the next succeeding budget year as available surplus unless its expenditure is otherwise authorized by law.