After the last day for the meeting of the Board of Review, the Assessor shall, upon receiving the certification of the several amounts to be raised, as provided in the preceding section, proceed forthwith to spread upon the assessment roll the several amounts determined by the Council to be charged, assessed, or reassessed against persons or property; and shall also proceed to spread the amounts of the general city tax according to and in proportion to the several valuations set forth in said assessment roll. For the purpose of avoiding fractions in computation, the Assessor may add to the amount of the several taxes to be raised not more than 1%; said excess shall belong to the city.