So here's a first for me. Booked JFK-SFO tonight. SDC'ed successfully to JFK-SEA-SFO - but it had a $9 tax addition. I'm used to multiples of $5.60 so this was a first for me
I ultimately called back in and changed again to JFK-PSP-SFO, and AFAIK there is no refund or anything. The purpose of this was to get better shots at upgrades, and this has paid off on (as of a few minutes ago) both flights.
-J.