for all it's worth
Whether or not it's significant or useful. Said of a statement that one acknowledges may not be considered helpful by the listener. For all it's worth, I think you should confront your boss if you're unhappy with how he's treating you.
for all it's worth
and for what(ever) it's worth if it has any value. (Usually implies lack of confidence.) My idea—for all it's worth—is to offer them only $300. Here is my thinking, for whatever it's worth. Ask her to give us her opinion, for what it's worth.