According to free products pricing tier, when a participant's order is discounted 100% when created, the minimum of $0.00 is charged in registration fees. Below is helpful information.
Registration orders can be discounted by adding a coupon code or discount that covers the total cost of the order.
If the discounts or coupons codes are removed from the registration, the participant will have a balance but registration fees still won't be charged.
Any registration adjustments will not trigger registration fee charges. The order will still have $0.00 in registration fees.
Note: Registration adjustments:
Transfers
Edit Purchases
Cancellations
Add/Remove discounts or coupon codes
To charge a registration fee the order will have to be canceled and the participant re registered without any discounts.