Pablo Osvaldo headed Roma back in front with his 11th goal of the season, but Manolo Gabbiadini hauled Bologna level again before the half-hour mark.
Bologna, who won 3-2 at Roma earlier in the season, went ahead for the first time nine minutes after the break when Cristian Pasquato took advantage of a mix-up in the Roma defense, before Tachtsidis headed in a free-kick in the 74th minute.
The action continued until the final whistle, with Alessandro Diamanti twice striking the woodwork for Bologna.
RSS