The City Finance Officer for good cause shown may extend the time for making and filing any return as required under this chapter, and may grant such reasonable additional time within which to file such return as he may deem proper. Provided, that any extension in excess of thirty days shall be conditioned upon payment of interest of one-half of one percent for each thirty days or portion thereof on the amount of the tax from the date upon which tax becomes due. If tax return and/or payment are not received within fifteen days of due date, a penalty must be included as follows: If sixteen to forty-five days delinquent, ten percent of the tax with a minimum penalty of one dollar; if forty-six to seventy-five days delinquent, fifteen percent of the tax with a minimum penalty of two dollars; if seventy-six or more days delinquent, twenty percent of the tax with a minimum penalty of three dollars.