Although Cheltenham look like being safe with Grimsby losing at home to Torquay, they more or less shut up shop at DVS as the Millers missed a host of chances and lost ground on third placed Bournemouth.
Kevin Ellison missed the hosts' best chance after 20 minutes, falling to his backside after being set up by Adam Le Fondre following Scott Brown's miskick in the visitors goal.
Ellison then shot just over, Le Fondre himself also fired wide and Pablo Mills had an effort cleared off the line late on as Rotherham failed to break down the visitors' resolute defence.
Cheltenham hardly crossed the half-way line but in a few rare forrays forward Josh Low was at the heart of their creativity.
The best chance of a goal came when Justin Richards headed just wide as the points were shared.