We reverted last week due to issues with 4.2.3 (see new threads). If we can resolve the issues on 4.2.3 regarding registation email and 'next step' button, then we can use the new version.
If not, then when we revert to 4.1.0 - the GST prices are showing 'rounded up' to the nearest dollar. They show this way on all of the prices.