As you can see above, the answer is that there is no answer. There is no regulation that tells you exactly how to convert your mil time to civilian.
Adding .2 or .3 to each sortie is a reasonable and quite conservative way to convert military (wheels up to wheels down) to civilian (wheel movement to wheel stop) time. The thing that you need to be able to do is to defend this as a reasonable practice to whoever is reviewing your logs in an interview. Every airline I know of has accepted this as allowable. I think most FSDOs reviewing logs in any sort of audit would do the same, but it wouldn't hurt to ask someone.
Clear as mud? This is why there is a logbook review in any sort of interview. There are people who will cheat or do dumb stuff. Don't be that guy. Adding .2 or .3 to each line in your logbook isn't cheating or being dumb.