You can only change komi by full point increments. There is a .5 to break ties, but a komi of 7.5 is identical to one of 7.4.
From a theoretical standpoint, any non-integer komi should lead to one player winning 100% of the time. So even if the actual win ratio is 14:6 at komi=7.5 that might still be the best value.
If you had an estimate of the real difference, you could switch to breaking ties randomly. Black wins 60% of the ties, white wins 40%. There will be a ratio at which each side should win 50% of the time.
I agree that with perfect play, it will be a 50% of a tie to each side. But it is still interesting to ask for a better estimate of practical play.
From a theoretical standpoint, any non-integer komi should lead to one player winning 100% of the time. So even if the actual win ratio is 14:6 at komi=7.5 that might still be the best value.