Susie, I think it also depends on the proximity to Manhattan, access to train station, and whether companies are there (because companies pay a lof in taxes so the tax becomes lower for residents in that neighborhood). I grew up in Westchester and am pretty familiar with the school system. Pocantico school system may be pretty good but it doesn't have its own high school; rather, the students get fed into Pleasantville, Sleepy Hollow and Briarcliff high schools. If students go to Briarcliff (good school), the taxes are super high. Pleasantville is middle because the school is average, and Sleepy Hollow is lower because the school isn't that good. But I do agree that taxes in Tarrytown is high in general regardless of the school district (perhaps it is because it is centrally located with access to Tappan Zee, NYC, White Plains, etc.). Ossining is also ridiculously high even though the high school is just average - I have no idea why. Do you find that taxes in Tarrytown, Ossining, Briarcliff, Scarsdale/Edgmont, Chappaqua are the highest? That is what I'm seeing.
I noticed that houses in Tarrytown with Irvington school are priced higher than houses in Sleepy Hollow. I also think families are much more apt to buy houses in places with good school districts rather than those that are not. I have been looking to buy in Westchester and I noticed that open houses in Chappaqua, Scarsdale, Edgemont are bustling while open houses in other areas are quiet.