Just a data point here...

I just entered at MSP declaring food using the kiosk and receiving the "circle receipt". The officer at the desk then proceeded to (apparently) process my entry manually, scanning my passport twice and typing information in to the computer before asking what I had. He then stamped my passport book and the BACK of the receipt so that the officer at the exit didn't see I had already been questioned before asking himself what food I had. It would have been quicker to use the regular line!