BOOKS AND BUCKS Continued from Page 35 ident's Men," yet never saw a dollar of percentage money. Why? One source explains, "Up front you had two stars, Robert Redford and Dustin Hoffman, with top-line percentages. They saw money, but the writers (including William Goldman, who did the screenplay) didn't." The new blanket term for this dilemma is "rolling breakeven." Questioned, sources often came up tongue-tied. "Everyone uses the term and no one understands it," says one. To simplify, a rolling "break" means that a studio can escalate the figure needed for a movie to recoup costs. Traditionally, a film that cost $2 million required a $5 million gross to break even. "Today, it's different," explains an agent. "Studios can tack on costs for advertising, distribution, whatever. It's tricky to keep track of. After an initial payment, the writer can still be in a difficult position." Or, as producer Jay Weston sums up, "What it really means is . ... more negotiation. Or, in some cases, higher up -front money."