"To cook the books" means to manipulate or falsify financial records or accounts in order to deceive others, typically for personal gain or to hide illegal activities. Full definition
Companies that are falling out of favour with customers and are experiencing declining sales and profits will often cook the books for a while. (canadianbusiness.com)
Authors of cook books have an advantage over traditional authors because they can employ a TV appearance to increase book sales. (book-marketing-expert.com)