Any person engaging in or prosecuting any business, profession, calling or vocation contrary to the provisions of this Part Seven, whether without obtaining a City license therefor before commencing the same, or by continuing the same after the termination of the effective period of any such City license may, in addition to paying the prescribed license tax or fee, be liable for a penalty of five percent (5%) for each month or fraction thereof during which he has been in default of such payment, plus lawful interest from date of default.
(1975 Code Sec. 10-12)