The City Council shall have the power to levy an occupation tax upon every occupation, profession, calling and vocation upon which an occupation tax is laid by the State of Texas; provided, however, that such occupation tax shall not exceed one-half of the amount exacted and required by the State of Texas. This tax shall be collected by the assessor and collector of city taxes and shall be paid by every person or persons, association of persons, firms or corporation which, under the laws of the State of Texas, are required to pay occupation taxes in the state. Provided, further, that nothing herein shall be construed to prevent the city, in the use of its police power, from prescribing license fees or police tax necessary and proper to enable the city to exercise proper police surveillance over all persons, firms or corporations, or calling subject to same.