While it's true that primary inspection agents will sometimes waive the duty amount, I don't agree with your advice. Answering "yes" to being over your duty allowance at a Nexus kiosk prints a dollar sign symbol on your receipt and directs you to the cashier. It does not automatically direct you to secondary unless you were randomly selected to go to secondary regardless of how you answered the kiosk's questions. And remember, the cashier also has the ability to waive duties.

So if you find yourself in a packed customs hall and the only think you have to declare is that you've busted your allowance, use the kiosk, get the receipt with the $ symbol and try your luck with the cashier. At the very worst, you saved yourself a whole lot of waiting in line.