wondering why they wont shutdown the processes completely when I close tabs.
Because there is something interfering, perhaps an add-on or other started program.
Try opening an IE window this way. Run... (e.g. press Win-R and enter:)
iexplore.exe -nohome -extoff
Use Task Manager's Applications tab to find that instance and right-click Go to Process. If you like, you can confirm that it is the one you started using the Command line field. Then close the window. The highlighted instance should go away.
If that is not enough to help identify a cause try doing the same test in a safe mode boot.