JoeMattock tested Boro stopper Paul Smith with an angled drive while United keeper Steve Simonsen kept out volleys from Scott McDonald and Rhys Williams.
The Blades had been chasing victory with substitute Marcus Bent guilty of missing a gilt-edged chance from Bjorn Helge Riise's corner on the edge of the six-yard box while JoeMattock lashed a 20-yard volley wide.