I filed amended state tax for an additional $1715 refund. When refund came, it was $1810, difference is maybe interest. What to file on federal taxes $1715 or $1810?

Your tax refund would be $1,715, so that would be the amount to use as taxable income from state tax refund. The additional $95 would be entered as interest income (form 1099-INT entry in TurboTax.)

I am assuming the state tax refund is taxable on your federal tax return, but that is not always so.