Ends in vowel (sound) = female: probably mostly true, in that I strongly suspect it's >50%, but it's unreliable enough that I'd avoid trying to base any assumptions off it.
Names really follow no rules at all here. For both good and bad. E.g. most recently I ran across a "La-sia" pronounced "ladashsia". If it's spelled vat-ik'Nff and pronounced "King George" and they're female, then that's what's correct.