In your climate they should be fine with little or no protection even in pots. A light freeze down to around 28 degrees shouldn't cause any damage at all. Anything lower and you will probably lose some cane length. If it's possible to put them in a garage or shed to protect them from the wind you could do that. But be careful because that may be too warm and they'll start to grow. If you start to get the pale green or white growth it's too warm and you may want to move them back outside. And you want to keep them watered even when dormant. I only keep my tree rose in the shed and I water mine at least once a month. Actually I usually dump a shovel full of snow on it every time we get snow. I keep my other pots on the south side of the house because that gets the most sun and warmth all winter but I'm way colder than you.

I live in Central Illinois. I don't cover my minis. They are planted in the ground.
For your potted minis just put the pots up close to the south side of your house and make sure the pots don't dry out put mulch on the soil in the pot.

In New England we could not overwinter our miniroses indoors. They always died. I put one outside one year and it came back.

I have had no problem overwintering roses in containers without protection. However, when/if temps go much below 20F, you should probably consider putting them in a sheltered spot. What you want to avoid is the soil itself freezing solid for extended periods.

Best not to bring the pots indoors; the plants do best when allowed to go fully dormant for a period of time.