Does the coupons.com printing uninstaller leave anything behind?
I don't really know specifically about the "coupons.com" printing software, but there are some ways to find out if there are some things left behind by the software. These are the best places to look:


Macintosh HD/Applications/
Macintosh HD/Library/Internet Plug-Ins
~/Library/Application Support/
~/Library/Caches/
~/Library/Containers/
~/Library/Logs (These are just text logs. No
real trace)
~/Library/Preferences/
~/Library/Printers/


If you need something more user-friendly or automatized, try the "CleanMyMac" app.

PD: The fact that it needs to quit your browsers it's actually a good thing. It might be removing plugins or extensions.