When I zoom with my Macbook's trackpad by pinch gesture, elements get blurry because of decimal zoom level like "169,11%".
Is there a way to change zoom steps to use only integers?
I don't know about adjusting the intervals. Since the motion of your fingers on the zoom is a fluid one, I doubt it.
Personally, I use CMD++ or CMD+- instead.
Alternatively, you can open your Navigator
(Window > Navigator) and use that. I always have mine placed at the top of my right-hand tool bar, for easier navigation, and you can click on the little/big mountains to zoom out/in.