Round a Decimal to two decimal places

• Daniel Ballinger

9 years ago

How can I round an arbitrary Decimal to 2 decimal places (hundredths of a dollar)?

My first thought was to use the Math Functions ROUND(number, numDigits):

Decimal toRound = 3.14159265359;
Decimal rounded = Math.round(toRound, 2);
system.debug(rounded);

But that produced the following compile error:

Compile error at line 2 column 19

Method does not exist or incorrect signature: Math.round(Decimal, Integer)

When I think of rounding I typically expect "Round half away from zero" tie-breaking behaviour. Maybe this isn't the best rounding approach to use with currency values? I would expect the following rounding:

• 1.004 to 1.00
• 1.005 to 1.01
• 1.014 to 1.01
• 1.015 to 1.02

The following works (to some degree), but seems a bit crude:

Decimal toRound = 3.14159265359;
Decimal rounded = Math.round(toRound * 100) / 100.0;
system.debug(rounded);

• 9 years ago

I don't think it gets more concise than this:

Decimal toround = 3.14159265;
Decimal rounded = toround.setScale(2);
system.debug(rounded);

What's nice about this one is you can use the setScale overload that lets you specify the rounding mode you want to use.

Decimal toround = 3.14159265;
Decimal rounded = toRound.setScale(2, RoundingMode.HALF_UP);
system.debug(rounded);

In this case - I think you'll want the HALF_UP rounding mode. It's the traditional round to nearest, but round .5 up. That does seem to be the common rounding method. Is there a rounding mode that would round 1.005 to 1.01 and 1.015 to 1.02? As in _round half away from zero_? Perfect, thanks. I've made an edit to include an example specifying the rounding mode as the web documentation doesn't. The code above, with HALF_UP specified, produces those results. It's worth noting that even though Salesforce calls this "HALF_UP", it is actually "Half Away from Zero" rounding. Traditionally "Half Up" rounds negative numbers differently, with -1.5 rounding to -1 (up; toward positive infinity). Salesforce's HALF_UP rounding, however, will round -1.5 to -2 (away from zero). Similar results are true of the other rounding methods in salesforce (DOWN == toward zero, UP = away from zero, etc..)