The problem with Roman blinds is that they have the ribs and string which in most cases you can't remove. If they are only lightly soiled and just need the dust removing, they should be cleanable leaving them up, good old vac with a hand held turbo vac, mist of microspliotter or m-power and towelled off
If they're more heavily soiled and need extraction cleaning, usually they're easy to take down, in which case they can be cleaned on some sheets on the floor. Don't forget you have to do both sides, and it is a bit of a faff so charge accordingly. They should eb re-hung and left extended to dry.
Roller blinds should be a bit easier, could probably be left hanging and extended to full length to clean and dry. But to be honest unless they are very expensive it might cost the same or more to clean them as buying a new one.