I figured out how to automatically show rounded times in invoices (ie. round times up to the next increment as specified in preferences).

Replace the SlipDuration token with the following dyanmic text, ensuring that "Evaluate entire text as mathematical expression" is checked. Then set the "Formatter" to "Duration (hours/minutes).

Here is the formula:



I hope this works for others. Seems a lot of people want it -- me included!

A straightforward solution for Billings ver. 3:

A script solution to invoicing in time increments