Please describe the problem:
When creating an invoice in the business module, and including tax amounts, the taxes are calculated on each line item.  Each tax amount is rounded to 2 decimal places.  When these tax amounts are totaled,  the total amount is often $0.01 greater than it should be.  The tax should be calculated on the total, before tax, invoice amount. 

Steps to reproduce:
1. Create an invoice with 2 line item amounts of $11.50 each.
2. include a 5% tax on both items.
3. 


Actual results:
The total tax on the invoice will be $1.16, when it should be $23 x 0.05 = $1.15

Expected results:


Does this happen every time?
yes

Other information:
Each individual line item tax should be rounded to 3 decimal places, and the total tax rounded to 2 decimal places.  This bug is a show stopper for me and makes the program unusable.