Broadway kept its grosses strong last week, pushing total sales up a bit from the previous frame to about $16.3 million and taking advantage of the last wave of tourists to visit the city before school starts in the fall.The roster of 24 productions on the boards saw few major bumps or dips. In perhaps the only sign of the impending September doldrums, the number of members in the millionaires’ club dropped to four for the first time in two months. (“Monty Python’s Spamalot” fell off by just $12,000 to $997,812.) “The Drowsy Chaperone” ($968,982) had a strong week, surging up by almost $95,000, while “Dirty Rotten Scoundrels” ($504,154) regained a little ground with a step up of nearly $60,000. “Faith Healer” ($386,806) played its final week to a $50,000 rise in biz but still didn’t achieve the vigorous sales it posted for the majority of its limited run. Among the newer offerings, “Martin Short: Fame Becomes Me” ($364,329) held steady at about 61% capacity. Producers are likely hoping for a boost from the publicity of the celeb-heavy opening night set for Thursday. Edgy cabaret duo Kiki & Herb played their first four Rialto dates, and while the show’s general management has yet to confirm grosses, early numbers indicate that “Kiki & Herb: Alive on Broadway” took in a bit more than $60,000 total for those initial perfs — suggesting that the production has yet to attract a crowd beyond its cadre of downtown devotees. The 21 musicals grossed $15,039,856 for 92.3% of the Broadway total, with attendance of 168,560 at 76.1% capacity. The three plays grossed $1,263,040 for 7.7% of the Broadway total, with attendance of 18,367 at 87.3% capacity. Average paid admission was $89.23 for musicals, $68.77 for plays and $77.49 for all shows.