Where the calculations come from can be obtained by a right click on the box and select data source. Sometimes, there is an additional line with more details.
When you click in a box, normal left click, and see a magnifying glass, select it to take you to where that number came from.
Why does TurboTax show $1 on my Iowa Schedule line 1A? Is it a rounding thing? The amount reported on Federal 1040 line 2b was rounded down by $0.22 from the total shown on Federal Schedule B.