It shall be unlawful for any owner or operator of any establishment within the scope of this article to post or maintain posted on outdoor or outside advertising signs rates for accommodations in any such establishment unless there shall be posted prominently and conspicuously in the area where guests are normally registered, a list of all rooms or other rental units offered for rental by such establishment, and the rates charged for each room when occupied by one person or two persons, and the rate charged for each additional occupant.