Thank you! That explains it for my case. The last two numbers on my taxable income were 98 so adding the "two dollars" on the interest I got pushed my total taxable income to the next $50 increment. 1.91 is not quite 2 dollars, so it doesn't seem exactly fair, but maybe there's a rule where if the total number would round up in cents to the next $50 increment it counts. Either way, I won't focus on it.
