I have usually lumped multiple items into a broad category such as clothing or books or toiletries. Of course, i have rarely broad back more than 4-5 items. The customs agents rarely ask any questions; they just take the form from you and wave you through (or occasionally grunt hello if I say good morning or some other greeting). I did witness one family being taken aside for further screening, but it was not apparent why they were selected other than the fact that they had a lot of luggage.