The early pressure came from Munster and they had the first scoring opportunity when awarded a 5th minute penalty for a high tackle but Hanrahan pushed his effort wide of the right upright.
However, he made no mistake six minutes later from an easier angle after a superb break-out of his own 22 by Ivan Dineen who took play to the opposition 22.
The visitors continued to pose problems, centres Eamon Sheridan and Lee Blackett combining to carve an opening that needed vigilant defence before Johne Murphy blasted a superb clearance to gain a 40 metre lineout.
James McKinney tied it up with a long range 19th minute penalty and edged his side in front with an even longer effort, from the half way line three minutes later.
In a game that continued to entertain, with Latu Makaafi offering his side lots out of touch and in the loose, and Toby Freeman another good lineout option, Rotherham extended the lead, again thanks to the McKinney boot after Johne Murphy had gathered a high ball on his 22 but Munster penalised for going off their feet.
Best scoring chance came with six minutes of the half remaining when old Titan Sean Dougall blocked Mulchrone's attempted clearance and Dineen was just beaten to the touchdown.
Alex Rieder made good ground down the left and from the ensuing ruck Scott Deasy intercepted and broke clear only to be whistled for offside by referee Simon Rees. It looked marginal and McKinney was marginally wide of the left upright with his penalty.
Having come second in the physical stakes in the opening half Munster needed a good start to the second and they got it when Hanrahan landed a 35 metre penalty with just three minutes elapsed.
He could have levelled three minutes later but was wide with a kickable effort as was McKinney minutes after, albeit from distance.
The game developed into a bit of a slugfest, fought out between the respective 10 metre lines but with Munster doing most of the pressing.
A neat Hanrahan dink thru looked to be yielding dividends when Deasy gathered but he was whistled back for being ahead of the kicker. Then Ian Nagle spilled the ball after cleverly finding a gap just inside the Titans 22.
With four minutes remaining Titans were penalised and their number six Alex Rieder sin binned and from a metre inside the Titans half Hanrahan levelled for a share of the spoils.
Munster A: Johne Murphy; Darren Moroney (Mullane 78), Ivan Dineen, Scott Deasy, Ronan O'Mahony; JJ Hanrahan, Cathal Sheridan; James Cronin, Sean Henry capt, John Ryan (Alan Cotter 65); Dave Foley, Ian Nagle; Brian Hayes, Sean Dougall, Barry O'Mahony (Ryan Murphy 61). Replacements: Niall Scannell, Alan Cotter, Philip Donnellan, Ryan Murphy, Brian Slater, Johnny Holland, Richie Mullane.
Rotherham Titans: F Mulchrone; P Homan, E Sheridan, L Blackett capt, J Gill; J McKinney, C Mulchrone; J Kilbane, T Stagg, R Davies; T Freeman, D Sanderson; A Rieder, L Makaafi, R Pitman. Replacements: G Denman, S Cahill, B Thomas, J Ellyatt, G Law, M Doneghan, J Williams.
Referee: Simon Rees (WRU).