Leaders Inter did their job by beating Chievo 4-3 at home but the agonising win for second-placed Roma kept them two points behind before next Sunday's final round of matches.
"Like a great team, we are able to manage our emotions and the pressure," Inter's Dejan Stankovic told reporters, looking forward to Sunday's trip to relegated Siena.
"It'll be tough but when is it easy to win a title? Never."
The battle for the fourth Champions League qualifying place will also go to the wire after Sampdoria, in fourth, drew 1-1 at fifth-placed Palermo following a penalty apiece.
Roma, who go to Chievo next weekend, started with Totti despite the striker being condemned in the media for kicking out at Inter's Mario Balotelli and being sent off in Wednesday's Italian Cup final defeat.
Media reports also said Totti will not be included in Italy's preliminary World squad on Tuesday after the Cup final incident prompted national coach Marcello Lippi to reject the striker's offer to come out of international retirement.
If the controversy was bothering Totti, he did not show it.
First he hit the post and the bar with Roma fans beginning to look desperate as news filtered through of Inter winning.
Cagliari scored midway through the second period thanks to Andrea Lazzari's free kick to further dampen the mood.
But Totti went from fallen hero to Captain Marvel yet again when he quickly equalised and converted a penalty seven minutes from time after Davide Biondini had handled.
BIZARRE START
Champions League finalists Inter, still on for an unprecedented Italian treble, had a bizarre start to their game with an own goal at each end within a minute of each other.
Inter midfielder Thiago Motta was unlucky to divert in Michele Marcolini's free kick on 13 minutes before Andrea Mantovani deflected in Samuel Eto'o's strike straight away.
Argentine midfielder Esteban Cambiasso then put Inter ahead with a well-taken goal from Maicon's cross on 34 minutes and compatriot Diego Milito netted a classy strike to score his 21st goal of the campaign in his first season with the champions.
Balotelli, so often at odds with his coach this term, made it four early in the second period before goals from Pablo Granoche and Sergio Pellissier sparked a nervy finish.
The colourful San Siro crowd lost their verve as Totti netted the penalty but had earlier reserved a special chant for coach Jose Mourinho given constant media speculation he may leave because given he says he is unhappy in Italian football.
Samp's draw will have allowed third-placed AC Milan a slight sigh of relief after Leonardo's side lost 1-0 at Genoa in a game played behind closed doors because of fears of fan violence.
Faltering Milan are now assured of third spot and direct entry into next season's Champions League because of a better head-to-head record over
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