Is it possible to hide a cashback toolbar but keep it functionnal ?

Hi Everyone,

Just wondering if you guys think it is possible to make a browser toolbar invisible (BUT functionnal) ?

Basically, what I want to do, is install a cashback toolbar on the computers of my family and friends, do get cashback from all their purchases. They all agreed to install it, but they don't want to see it in the browser.

So my question, is it possible to make a toolbar invisible BUT functionnal ?

If it is possible, is this something complicated to program ? I am willing to hire someone to program this for me.

Thanks!
James