Yes. If your class is using free instructional materials (free textbook, homework, lab manual, etc.), but you require other things with an associated cost (e.g. lab safety equipment, art materials, attending a live performance), you can still add the ZTC symbol to your course. 

However, a state law (AB 607) does require transparency in all course material costs. This means you should report estimated costs either through the bookstore or with a class section note. This slideshow walks you through that process: Reporting Material Costs and Adopting Supplies at the Los Rios Bookstore