Wis. Stat. § 202.15
If a commercial coventurer conducts a charitable sales promotion on behalf of a charitable organization that is required to be registered under s. 202.12(1), the commercial coventurer shall disclose in each advertisement for the charitable sales promotion the dollar amount, or percentage of price, per unit of goods or services purchased or used that will benefit the charitable organization or charitable purpose. If the actual dollar amount or percentage cannot reasonably be determined on the date of the advertisement, the commercial coventurer shall disclose an estimated dollar amount or percentage. The estimate shall be based upon all of the relevant facts known to the commercial coventurer and to the charitable organization regarding the charitable sales promotion.
Wis. Stat. § 202.15