In Zone 5 you most likely won't be able to leave them in 8" pots on the patio over winter but your cold dark basement sounds like it might be usable. Keep them slightly moist but not overly wet so the roots won't dry out. Covering them with black plastic will keep them in the dark until you want them to start to put on new growth closer to spring time.
However, the best way to over-winter them would be to sink the pots into the ground and cover with a leaf mulch.
Then next spring once the danger of frost is past, you can lift the pots and bring them back to the patio to enjoy close up.
BTW...8" is a bit small for a mini and you might want to consider moving them to a larger pot, 10" - 12" would do well for them.
I wouldn't prune them back once the cold weather sets in. You can prune or cut them back in the spring once you see if any of the canes have died over winter or are diseased or damaged.
You should notice that they most likely will bloom well into November given the type of care you are giving them.
Bringing minis inside is asking for lots of problems as minis really aren't house plants. Spider Mites love indoor minis and will eat your plants alive (pun intended)!
Good Luck with your babies!
Hope this is helpful.
Meg

So I can leave my minis in 12" pots permanently? I was planning on putting a plastic bag over them this winter and leaving them outside. In my corner of Indiana, it stays pretty well above freezing for most of the winter and rarely ever goes below zero.

Lacy:
Your roses will need a period of cold and dark.
If they are exposed to lots of daylight, it will encourage them to grow even during the winter months.
You need to give them a rest period and both darkness and cold is necessary to accomplish this.
Enclosing them in a plastic bag may allow mildew to get started.
Meg

I grow minis in pots year long along my driveway. Minis are hardy plants and don't need any protection. Potted minis out of the ground should be set into the ground to protect the roots. If you want to add mulch go ahead but it's not needed. Just make sure the pots are well watered. If the plant is in good shape going into winter, it should come out in good shape.