Donald Trump has rarely had anything nice to say about Mitt Romney, but when it comes to tax returns, the Republican nominee treats his predecessor as a cautionary tale.Trump has long refused to release his tax returns, saying that he is currently under audit. But asked Thursday night by Fox News’s Greta Van Susteren if he would release older tax returns that are not under audit, Trump said the beating Romney took in 2012 over his own tax returns should serve as a warning.“I remember with Mitt Romney four years ago, everybody wanted his, and his is a peanut compared to mine.