I used to, well more than 10%. I left my religion a few years ago, continued to pay until about a year ago. A few years ago I would have happily defended my churches purchases and wealth, now I find it horrifying. It's tend to hide it's financial information, but it was leaked a month or so ago that it had more than £100 BILLION in reserves, the church accepted this but tried to justify its wealth.
I guess a few years ago I would have defended it saying it was wise to protect its money and we don't know what the future brings, but now I know it's charitable spends are around 6billion, which is generous but in comparison it's a drop in the ocean. I can't help but think they often take from the poorest people, encourage those to pay in faith even if it leaves them short on rent or for food etc and it has that much wealth, so much can be done with that.
I'm perhaps over critical because of my experiences with my past religion but it makes me uncomfortable.
So I have given, now I don't, I do give to charities and I do give a lot of my time to volunteering but I'm fortunate enough to be able to do that. Plus I am saving thousands a year from not giving to a church.