Some Costco customers are crying fowl over the big-box chain’s popular $4.99 rotisserie chickens, saying they contain preservatives in spite of the company’s claims to the contrary, according to a new lawsuit. Two California-based people say Costco “has systematically cheated” consumers “out of tens — if not hundreds — of millions of dollars” by advertising the poultry as being free of preservatives. The class-action lawsuit, filed last week in San Diego federal court, alleges that Costco makes the claim despite the fact that the rotisserie chickens contain sodium phosphate and carrageenan.