It does explain it thuroughly in the rules somewhere.
When it's tied it looks at the final 9 holes - whoever has lowst score in back 9 wins. If it's still tied it's the final 6, still tied final 3, still tied goes hole by hole starting with 18 and counting back. Still tied whoever posted the score first.
For Ready-gos it seems the top one is decided on same way but every score after that is ranked the same. Currently 2nd in one myself on countback despite having same score, but I also once won one on countback so evens out in the end I guess...