How MarketPress calculates the price(s) in the invoice

Prices are entered as including 10% GST so the software has to calculate GST to display on the invoice. The problem is that the software is also calculating the net of GST price. Both of these amounts are rounded to a dollar and cents value (2 decimal places). The problem is that it is not checking that the sum of these 2 values add up to the original GST included price. Is there an option to not make calculations this way or is this a possible bug on the plugin?