State tax filing

My situation is getting more complicated. I imported my 1099 from Schwab and then input the amount of individual Tax-Exempt Bond income by state using the easy step form.  The amount being reported on 1040 line 2a matches what I get when I subtract total bond premium from total tax exempt interest. Good up to this point. I compared this to the total tax-exempt on CA Int/Div/Adj worksheet line A. There is a $3 difference. I think this may be how TT handles rounding--I put all my amounts in with dollars and cents. I can understand this I think.

 

However the amounts on the CA worksheet for CA Tax Exempt interest and non-CA Tax Exempt income don't match anything. I've built a spreadsheet with every Bond, all the bond premium, etc and tried every combination to get to those numbers.  The closest I can get (within a few $s) is if I distribute all the bond premium on the same ratio as CA bonds to total Bond versus applying CA Bond Premium to CA interest. It appears to be:

 

CA Tax-Exempt Int / TTL Tax-Exempt Int = CA Bond Premium / TTL Bond Premium

 

 

So my revised questions:

 

How does TT handle Bond Premium to calculate tax exempt interest at the state level? Using specific numbers or on a ration basis like above?

 

How does TT handle Rounding?

 

Are there other worksheets within TT I can reference to see how the interest and bond Premium is being handled?

 

Thanks