Yes, I'd say roses do need dormancy. However, how much, and how often varies quite a bit. Repeat bloomers with a lot of semi-tropical heritage, like most modern roses, don't need to go dormant every year. So skipping a winter is fine. With that out of the way . . .

Roses are not people. They aren't even cats. What they consider cold isn't what we consider cold. Also, most modern roses are stupid when it comes to cold. So they don't consider going dormant until temperatures are around freezing, and even that isn't necessarily enough. My guess is that you put them away far too early, and they never got the message winter is coming. It also sounds like your garage is too warm to keep them dormant. Even in zone 6, keeping the pots outside against a house wall can be a better strategy. Particularly if you can move them into the garage when it gets cold, below 20°F.

So what do you do now? It sounds like they are reasonably happy where they are. Just keep them above freezing, and don't worry if they are in a place that you consider cold. Temperatures in the high 30's would help slow them down, so wouldn't be a problem.

The big issue is going to be when it starts warming up again in the spring. As the temperatures increase, the roses will need more light. They will have to go outside. Then when it goes below freezing, they will have to come back in.

So-called everblooming habit of popular modern rose types like hybrid teas traces back to warm climate garden roses like chinas and teas developed from soft climate species like Rosa chinensis and R. gigantea. So, examples of even tropical places where such kinds are seen being grown are chinas in Bermuda - known particularly as a source for certain antique varieties - and hybrid teas in Hawaii. With, in the latter case a hibiscus collection in a frequently seen public park in Honolulu being replaced with a bed of assorted hybrid teas some years ago. That said hybrid teas in Hawaii do seem to be affected by the fact that they never take a break in that long, straight stems with jumbo flowers on the ends are not the default mode. That their apparent inclination is to be more twiggy and smaller flowering under tropical conditions. But they still do well enough without any frost or associated shutting down to have had a history of appearing at garden centers in Hawaii every winter. Same as here on the mainland.

I live in a zone that doesn't get cold enough to really send roses into dormancy. In late fall I stop dead-heading and watering and fertilizing. In January, I do the pruning and strip all leaves off, and within a couple of weeks they all have fresh buds and tiny new leaves. They seem to do fine. Our lows can get into the 30s, but I think we've only had frost at our place a few times in 20+ years. Most overnight lows are in the 40s or 50s. I imagine that when you're ready to take them outside in spring you might do your regular routine and they'd be fine? But I'm not from your zone...so what do I know? I just know that I don't get any real dormancy here, and there are tons of happy roses in So Cal!

The short answer is no. They don't need dormancy.

Now chill hours is a real need for some Old Garden Roses...much in the way that ssome fruit trees need a certain number of chill hours. If you're only growing modern roses, then you probably don't need toto worry. as Deborah explained