They don't appear together in my list of good/bad companions. I have never grown roses, so I don't know the conditions they like, but mint likes its soil constantly moist, and it is susceptible to a fungal disease commonly called 'rust'. Roses are also susceptible to rust, but I don't know if it's the same one as mint.

You DO know, don't you, that mint is an absolute THUG in the garden? I'd be more concerned about keeping the mint under control, and about planting a heap of different mints together. The ones which self-seed will cross-pollinate, and when mints are grown together like that, the flavours intermingle into something completely and utterly awful.

I suggest uprooting those mints and putting them into large containers - separately. You'll have to report on a regular basis, as those roots are really, really aggressive growers!

Why not plant chives or garlic chives under your roses instead? Much more manageable, and the chives (especially the garlic chives) will attract aphids away from the roses. Pretty flowers on both.

Other companions for roses include:
French Marigold, Fruit Trees, Garlic, Hyssop, Lavender, Lemon Balm, Nasturtiums, Parsley, Rue, Sage, Tansy, Thyme, Tomato.