35 ILCS 115/7
It is unlawful for any supplier to advertise or hold out or state to the public or to any serviceman, directly or indirectly, that the tax or any part thereof imposed by Section 3 hereof will be assumed or absorbed by the supplier or that it will not be added to the selling price of the property sold, or if added that it or any part thereof will be refunded other than when the supplier refunds the selling price and tax because of the merchandise's being returned to the supplier or other than when the supplier credits or refunds the tax to the serviceman to support a claim filed with the Department under this Act. Any person violating any of the provisions of this Section within this State shall be guilty of a Class A misdemeanor.
35 ILCS 115/7