For tournaments without a fee/rake (rare, but they do happen) they have the buy-in doubled instead of having the fee recorded as $0.
For example, if you play a tournament with a buy-in of $5+$0 it gets recorded as a $5+$5 in PT3, if you play a tournament with a buy-in of $10+$0 it gets recorded as $10+$10, and so on. I cross checked all of my no-fee tournaments in PT2 & PT3 and the result the same for all of them.
