Before I became a GlobalEntry member, I often was questioned about why I was bringing back so little stuff from a European trip. I usually said "I wasn't there long enough," or "I just took pictures," both of which were the truth. I like to travel light, so I'm not going to buy a bunch of junk, t-shirts or otherwise. Plus, I'll be going back there soon enough.

Remember that you should not declare funds spent overseas unless you are bringing back physical goods with you. So your hotel, restaurant, transportation costs, etc., should not be included.

Remember, also, to be truthful during any questioning by CBP officers. As the earlier poster noted, it's better to declare it and pay a couple of dollars of duty (which the officers are likely to waive) than not to declare it and risk fines and confiscation.