"I agree with so much of your post, let me zero in on the one place we
differ. I almost always leave exact change including the tip so that the
server needn't bring me anything back. I'm sure many others do the same.
With the answer so often being "we're all set," I couldn't blame the
server for asking that question to everyone without looking at the check
or the dollar amount to see if the question makes sense. So I don't
punish the server for asking. I just say "yes, I do need change" and tip
normally.
--Lia"

Sorry...I should have been more clear...
I mean I've been asked that AFTER the waiter looks at the amount I hand
him with the check!

I too try to leave the exact amount...but it doesn't always work out
that way.