I would argue you have the stick by the wrong end. The question is not, will blogging help me sell books. The question is, do you want to blog. If you do, then go ahead and don't worry about its effect on sales. You're blogging because you have something to say. A *lot* to say. For years.
This. Definitely. There are plenty of writers who don't blog. You do need some web presence, but it can be something else if this isn't your cup of tea.
And remember, blogging doesn't have to be super-serious-long-post stuff. A published author friend of mine writes haikus on her blog - snippets of her life accompanied by a photo.
When I started blogging, I wasn't sure I wanted to do much with it. So I started out microblogging on Tumblr; just an image and a couple of lines, or a short paragraph. But then the paragraphs began to grow because I started enjoying it, and eventually I moved my blog over to Wordpress - I've been going for a couple of years now.
If you do decide to start a blog, think of the angle you want to use, and what subjects you find interesting. I know that I'll always find good posts on writing on @Jo Zebedee's blog, for instance, while on @thaddeus6th's blog there's always cool history stuff. Don't just promote your work; give people a reason to return.