Project billing rounding

Set billing rounding on a Time Tracking project. Exact time remains the default. When tracked time is added to an invoice, Magpie calculates the new item amount from the billed duration and hourly rate. The picker shows recorded and billed duration when they differ. Saved time entries keep their exact duration, and changing the project setting does not reprice an item already on a draft. CSV exports include recorded and billed duration, the rounding increment and the calculated amount.