Upon receiving the certification of the amount to be raised, as provided in the preceding section, the Assessor shall proceed to spread the amounts of the general City tax upon the assessment roll according to and in proportion to the several valuations set forth therein. To avoid fractions in computation on any tax roll, the Assessor may add to the amount of the several taxes to be raised not more than the amount permitted by law, which added amount when collected shall be credited to the General Fund of the City. Assessments and other lawful charges authorized by the Council to be spread against or charged to property or persons upon the roll shall also be spread and charged thereon as directed by the Council.