Hello,
Assuming that your Currency Decimal Digit is 2, here is how I would expect your amount of $23.7406 to round.
Up to the Next Currency Decimal Digit = $23.75 (Essentially always round up)
To the Nearest Currency Decimal Digit = $23.74 (Round up or down, whichever is closer)
Now if your Currency Decimal Digit is 3, here is how I would expect your amount of $23.7406 to round.
Up to the Next Currency Decimal Digit = $23.741 (Essentially always round up)
To the Nearest Currency Decimal Digit = $23.741 (Round up or down, whichever is closer)
If you open the Tax Detail window (Administration >> Setup >> Company >> Tax Details) and go to Help>About this Window, under the Fields tab is has the following explanations.
Round:
Determine how tax calculations will be rounded. Choose from the following options:
Up to the Next Currency Decimal Digit
Select to round numbers to the next currency decimal digit. For example, if the tax amount is calculated to be $1.563, the tax will be $1.57.
To the Nearest Currency Decimal Digit
Select to round numbers to the nearest currency decimal digit. For example, if the tax amount is calculated to be $1.563, the tax will be $1.56.
Down to the Previous Currency Decimal Digit
Select to round numbers down to the previous whole digit. For example, if the tax amount is calculated to be $1.3306, the tax will be $1.33.
Up to the Next Whole Digit
Select to round numbers up to the next whole digit. For example, if the tax amount is calculated to be $1.263, the tax will be $2.00.
To the Nearest Whole Digit
Select to round numbers to the next whole digit. For example, if the tax amount is calculated to be $1.26, the tax will be $1.00. If the tax amount is calculated to be $1.51, the tax will be $2.00.
Down to the Previous Whole Digit
Select to round numbers down to the previous whole digit. For example, if the tax amount is calculated to be $1.563, the tax will be $1.00.
I hope this helps!
Isaac Olson
Microsoft Support