Sorry it's so late coming, but I just saw your post. Trust this advice, 'cause I'm an expert.
1. When your ship visits the U.S.V.I. (Sts. Thomasm John or Croix) the U.S. customs personal exemptions change radically. You don't have to acquire all your stuff in the V.I., just as you stop there. OK soo far?
2. Each member of your household, including children, is allowed a $1200 duty-free exemption for goods brought back to the U.S. The exemptions can be combined (e.g. if you see a $3000 necklace in Cardows and there are 3 in your party, you can combine the three exemptions - $3600 - to get the piece duty-free).
3. Included in your exemption(s), except for minors, are 1000 cigarettes (5 ctns.), 4 ctns, of which must have been bought in the V.I. So you can buy one carton in Nassau or wherever, but the rest must be acquired in the U.S.V.I.
Warning: if somebody tries to sell you Cuban cigars anywhere in your travels, just say "no thanks". No matter what you might be told, they are absolutely prohibited from entry to the U.S. Most legitimate shops won't even try to sell them to pax on u.s.-bound ships.
4. Included in your exemption(s), except for minors, are 5 liters of alcoholic beverages, bur one of them has to be of V.I. origin. So you can get 4 jugs of scotch, gin, etc. and 1 more of V.I. rum or liqueur for example. So two adults can bring back 10 liters total as duty=free. However, most cruise ships won't let you keep possessionof the booze in your cabin, but will hold it for you until you disembark.
5. Finally, Donna, if you go wild and spend beyond your exemptions, fear not. If you do exceed the above-stated exemptions, you must show it on your U.S. customs declaration and meet with the Customs inspectors on board (about 6:30 am) on your disembarkation day. The customs duty/tax will only amount to 2% of the 1st $1000 over your $1200 exention (about $20) and slightly more if you really charged up a storm. Just be sure to fill out a complete declaration if you're over your allowance. If you stay within your $1200 & your tobacco & liquor quotas, you do NOT have to list all your purchases on the back of the customs declaration. And remember, NEVER try to fool a Customs Inspector! They've seen it all and heard it all, and they come down hard on what they fondly refer to as "chislers". Happy cruzin!