OK, a little further exploration lets me explain how the transformation behaves. Numbers in the worksheet display only as many significant figures as required. So as you originally observed, $2341.40 displays as $2341.4. And $975.00 displays as $975. Notice that the thousands delimiter is also absent.
However, if the display is also limited by the number of decimal places set for base currency. So, if you set that to 1, $2341.44 would display as $2341.4. (This is what I originally tried.)
Not being personally familiar with lodgment of New Zealand GST filings, I don’t know if this is by design or accident. But I will observe that the behavior is just like typical spreadsheets. You see only what is necessary for the precision of the calculation. But you can also truncate numbers.