Once we (2 of us) came back through customs with 12 bottles of rum and had to pay a small duty (maybe $15). Another time we had 9 bottles of rum and 1 rum cream and they looked at us sternly and said to not do that again.
I am always up front with them about the amount because lying to the customs people is a crime.
Respect,
Col. Andy & "Wildcat" Pam
