Although the overall Broadway cume fell last week — blame the prior shutterings of a couple of mega-selling limited runs — the majority of Rialto offerings posted gains.Most notable among the rising tallies was the continued upward spiral of “Irving Berlin’s White Christmas” ($1,268,196), which muscled its way up to No. 4 on the B.O.’s top 10 with the help of the approaching holiday. New David Mamet play “Race” ($686,409) was up by a hearty 22% despite the mixed notices the production earned last week. Meanwhile, “Fela!” ($521,512), climbing by 26%, looks like it may have begun to reap the benefits of its glowing reviews. Fellow new tuners “Memphis” ($660,887), “Finian’s Rainbow” ($603,814) and “Ragtime” ($517,741) also rose, but by smaller degrees. And with its new cast still settling in, play “God of Carnage” ($548,908) held nearly steady. None of the week’s individual drops proved particularly remarkable, with the largest of them, “A Little Night Music” ($686,680 for seven perfs), attributable to the fact the last week included the show’s heavily comped press previews and its opening night. Still, total Broadway sales slid $2.2 million to $20.8 million for 30 shows on the boards. That’s mostly due to the fact that missing from the week’s lineup were two big-money earners — “A Steady Rain” and “Hamlet” — that both ended their limited runs Dec. 6. With the Sunday closing of Manhattan Theater Club’s revival of “The Royal Family” ($184,471), the Rialto lineup is now set until the post-holiday shutterings that come every year in early January.