Sometimes when applying a write-up/down (WUD) to an invoice, small rounding errors occur. Why does this happen?
To explain why it happens consider this example:
Imagine there are 11 time entries worth $100 each for a total of $1100.00 and you want to write this down to $1000.00. If you apply a write-down to all the 11 time entries, then you will have to write down each entry by a value of $100 / 11 = $9.090909090. However, if you have only two decimal places to work with, the value of time entries after the write-down will be $90.91.
11 time entries worth $90.91 = 11 x 90.91 = $1000.01, so there is a $0.01 rounding error. As there is no automatic resolution possible for this, here is how to deal with this:
1. Apply the write-down to a fewer number of time-entries. In the Write-up/Down screen, apply the change to only 10 entries out of 11. The calculation comes out evenly then.
2. Alternatively, use a Manual Invoice. A more accurate rate of 90.9090909 can be entered here.