I successfully root with towelroot @ http://towelroot.com/.
The site looked sketch but I did some research and the guy is from XDA and designed it for the s5's. But I took the chance and it works!!! Screen shoot attached.
(I know the screen shot doesn't provide 100% proof, but its the best I can do at the moment)
This root Method doenst seem to work if your kernely is < June 2 2014. Look in the kernel build in your device settings and if its before June, then I dont think the root method will work for you.