It shall be unlawful for any person, corporation, partnership, firm, limited liability company, association, proprietorship, or other entity engaged in or continuing within the county any business for which a license or privilege tax is required by this part to fail or refuse to add to the price of the service rendered the amount due by the taxpayer on account of the tax levied by this part. Nor shall any such person refund or offer to refund all or any part of the amount collected as tax under this part or to absorb such tax or to advertise directly or indirectly the absorption or refund of such tax or any portion of the same.