Cable grommets for use with raised-floor tiles permit the passage of cables while simultaneously limiting the amount of cool air escaping from under-floor ducts and plenums. The cable grommet includes a floor tile mounting flange, one or more pairs of opposed, overlapping finger assemblies, and one or more pairs of opposed finger mounting flanges for coupling the finger assemblies to the underside of the floor tile mounting flange. The edges of the of the triangularly-shaped fingers are configured to flex around the cables while the interior core section remains generally rigid and parallel to the plane of the floor to restrict the loss of cooling air. Alternatively, the cable grommet includes a floor tile mounting flange and a finger panel defining a sinusoidal cut along its length and a plurality of intersecting short cuts.