Your $5,500 nondeductible contribution gives you $5,500 of after-tax basis in your traditional IRAs. If this is your only traditional IRA account, converting the entire account, $6,620, will result in the calculations on Form 8606 determining that $1,120 of your Roth conversion will be taxable and $5,500 will be nontaxable. There is no penalty on a Roth conversion.
