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."
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.
Cagliari scored midway through the second period thanks to Andrea Lazzari's free kick to further dampen the mood.
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.
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
