I finished rooting the galaxy s5 g900v phone.
0) back up all your data. Titanium backup pro is the easiest way. Backup ALL user and system apps+data. Trust me, do this!
1) you must downgrade from 5.0 to 4.4.2. get original verizon os from sammobile. Don't need to be rooted to do this, just use odin 3.09. Download the newest 4.4.2 which uses the NE9 kernel. Sadly you will have to wait 8+ hours for it to download, because sammobile has slow servers. Trust me, there isn't a faster alternative that's safe so you just need to wait.
The correct OS to download will contain this: G900VVRU1ANE9
Use this guide to do the downgrade:
http://androidforums.com/threads/verizon-downgrade-to-kitkat-dummies-guide.902737/
1b) You will probably get bootloop (stuck on verizon screen), don't worry just take out battery and reinsert and boot into recovery and Clear Cache. Hopefully you backed everything up beforehand, so if all your data is safe then just go ahead and wire data/factory rest (still in recovery). Clearing cache AND wiping data is the cleanest way to do the downgrade, to prevent potential future issues, so this is highly recommended.
Use this guide to help fix any problems you might encounter:
http://androidforums.com/threads/s5-lollipop-update-problems-dummies-guide.892800/
2) after successful downgrade, root using towelroot.
Rooting with towelroot is easy, just download tr.apk from the official towelroot site and drag it to your phone and install it and then make it ra1n.
use this guide to root with towelroot:
http://galaxys5root.com/galaxy-s5-root/how-to-root-att-or-verizon-galaxy-s5-towelroot/
2b) If you are on 4.4.2 and towelroot says not supported, it's probably because you used the newest (and better) NE9 4.4.2 version. NE9 is the kernel name. You need to flash the NCG kernel in odin, reboot and root with towelroot and install and update supersu, and then reflash the NE9 kernel.
Use this guide that shows you how to flash the kernel:
http://www.andromods.com/root-unlock/vzw-galaxy-s5-rooted-g900vvru1anha.html
Wherever it says "NHA" in that thread, do NOT use NHA, instead use NE9 kernal in the link below (located in the "kernels.zip" folder).
(DON'T use the NHA kernal! It would cause a bootloop because it's the wrong kernal. You will have to get the NE9 kernal from here:
http://rootjunkysdl.com/getdownload.php?file=Galaxy S5/NE9 Root/Kernels.zip )
3) you are now rooted. congratulations! Use titanium backup to manually restore all your applications, application data, and system data including messages, call history, etc.
It worked for me. Sorry for the limited instructions, I don't have the time to do a full writeup, you will need to use the listed thread guides in the links I gave you for full instructions.