In January 2017, I contributed the maximum ($6500) to a traditional IRA for the 2017 tax year. (I'm over 50, so can contribute $6500.) This month (September 2018), I finally got around to doing my 2017 taxes, and noticed that my marginal tax rate is low (10%). So I called my investment company (Vanguard) to recharacterize my traditional IRA contribution to a Roth IRA. Vanguard did so, but apparently because of fractions of shares, moved $6500.04 over; in other words, 4 cents extra. (I have plenty of other money in my traditional IRA account from previous 401(k) rollovers.) I don't really care about the 4 cents, but I want to make sure I won't have to pay a penalty (large or small) to the IRS for an excess contribution.
Am I liable for a penalty? Do I have to do something to avoid one? Do I have to do anything special on my 2017 or 2018 tax returns? Thanks.