Having the steering wheel, even slightly, out of alignment when straight ahead is so annoying, I can't stand it.
The best way I've found of straightening the wheel, is to change the tracking of each front wheel by screwing the tie rods in or out, exactly the same on each front wheel. It is a bit of trial and error, but does work. A word of warning though, just make sure that both wheels are moved in the same direction, it's really easy [for me at least] to move the wheels in opposite directions, and lose your toe measurement completely. I mark the track rod end with a small dab of white correcting fluid to indicate the amount of thread used.