$0 Price: Invalid Data.

I’ve got a special option for registration where the registrant price is $0. The registrant can enter all of the requested information, but when it gets to the end an error comes up saying
“This transaction cannot be processed. The amount to be charged is zero.” The registrant information is recorded, but because of the message given to the registrant they believe an error has been encountered. Is there a way to bypass or suppress the error for this scenario?