If I were Trump, I would not provide them at all. This is a fairly recent phenomenon that candidates supply their tax returns in addition to their financial disclosure filings.
Trump does not prepare his tax returns. An army of accountants do. He is audited annually by the IRS. Why do we need to see them? The obvious answer is for his opponents to go thru them to find something embarrassing or negative. Below is a picture of Trump signing his 2014 returns:
Bernie just released a year of his tax returns. His annual income was less than Hillary made for one speech. Hillary still refuses to release the transcripts of her speeches to Goldman-Sachs. I would say Trump has a bargaining chip to use against Hillary in the fall.