Lets say I shoot 65-70 spine parallel wood shafts and want to order some that are tapered at the nock end, will this change affect spine enough, that I need to go up in spine to a 70-75?

If you're ordering your shafts already tapered, just order them at 65-70.  Tapering reduces the weight by a pound or two, but since you're not ordering parallel shafts and tapering them yourself, there's no need to order them any heavier than you normally would.

Orion is right, and since most of the bending takes place in the middle, tapering will have little effect either way.

Smallwood,
In my experience with rear tapering arrows,i loose about 3 lbs of spine fairly consistantly.I spined before and after tapering to see for myself.

You should do fine ordering your regular spine.  I spine all mine after tapering and match them that way.  When I've checked it, I only lose about 2 lb in the tapering process.  Go for the tapered shafts, I believe you will like how they fly.

Here's a different take on it. if you shoot 70-75 spine woods and they work great. Now you taper them and only lose 2-3 pounds, now let's say that out of the dz shafts 8 of them are 70# (before tapering). You now end up with 67-68# spine after tapering. I have seen this over and over when ordering wood shafts. I order 70-75 spine and after they taper them I get 65-70 spine group shafts. You would think that who ever you buy them from would spine check them after tapering. I feel if I order 70-75 tapered shafts then all 12 of them should be between 70 and 75 after tapering, c'mon that's a 6# range.