Selena, the duty free limit is small - basically, only a bottle or two. But here is the good news: I have come back from overseas (Europe, Australia/New Zealand and South America) carrying wine many times, sometimes as much as a case, and I can tell you that it's not a problem. You need to be honest and declare it, but customs has never, ever bothered to collect the duty. It's very small - only a dollar or two per bottle at most - and they just don't fool with the paperwork. Even if they did, it wouldn't amount to much, but they don't.
Don't try to hide the wine and don't lie about having it. That approach WILL get you in trouble. But just fill out the form, hand it to the nice person at the end of the line and smile, and they'll wave you through.
The only problem I could imagine would be if someone came back with so much wine of very large value that they became suspicious you were bringing it back to sell rather than for your own use. Commercial imports require a LOT of paperwork. But as long as you're not bringing in more than you can carry, that's not going to be an issue.