tag
This is what NF has to say about it. The video essentially says that if your image is clear and you still have parallax, go back and revisit your diopter setting to refocus the reticle. Seems to me that if you follow what this video is saying, you could remove parallax error, then adjust your diopter until the reticle and image are in focus.
That said, if your NXS is anything like a couple I've had, no amount of diopter fiddling will correct it.
It's worth a try though.