ACC2000: How to Round a Number Up or Down by a Desired Increment (209996)

SUMMARY

This article shows you how to create a procedure that rounds a number up or down by a specified increment. For example, given the number 3.23, rounding to the nearest .05 results in the number 3.25. The procedure in this article accepts any positive rounding increment as a parameter. In addition to rounding numbers to the nearest fractional amount, you can also round to whole numbers, such as 1, 10, or 100.

Microsoft provides programming examples for illustration only, without warranty either expressed or implied. This includes, but is not limited to, the implied warranties of merchantability or fitness for a particular purpose. This article assumes that you are familiar with the programming language that is being demonstrated and with the tools that are used to create and to debug procedures. Microsoft support engineers can help explain the functionality of a particular procedure, but they will not modify these examples to provide added functionality or construct procedures to meet your specific requirements.

MORE INFORMATION

The following example creates a user-defined function called RoundToNearest, which accepts three parameters:

Parameter	Value
dblNumber	The numeric value you want to round
varRoundAmount	The increment to which dblNumber will be rounded
varUp	An optional argument: include to round up; omit to round down

For example:

RoundToNearest(3.33, 0.1, up) returns the value 3.4.
RoundToNearest(3.33, 0.1) returns the value 3.3.

Create a module and type the following line in the Declarations section if it is not already there:
```
Option Explicit
```

Create the following procedure:

Function RoundToNearest(dblNumber As Double, varRoundAmount As Double, _
   Optional varUp As Variant) As Double
            
   Dim dblTemp As Double
   Dim lngTemp As Long
      
   dblTemp = dblNumber / varRoundAmount
   lngTemp = Clng(dblTemp)
      
   If lngTemp = dblTemp Then
         RoundToNearest = dblNumber
   Else
      If IsMissing(varUp) Then
         ' round down
         dblTemp = lngTemp
      Else
         ' round up
         dblTemp = lngTemp + 1
      End If
      RoundToNearest = dblTemp * varRoundAmount
   End If
End Function

To test this function, type each of the following lines in the Immediate window, and then press ENTER:
```
?RoundToNearest(1.36, 0.25, up)
```
Note that the procedure returns 1.5.
```
?RoundToNearest(1.36, 0.25)
```
Note that the procedure returns 1.25.
```
?RoundToNearest(1.36, 0.75, up)
```
Note that the procedure returns 1.5, which is two increments of 0.75.

REFERENCES

For additional information about rounding, click the article numbers below to view the articles in the Microsoft Knowledge Base:

210564 ACC2000: Round or Truncate Currency Values to the Intended Number of Decimals

210423 ACC2000: Rounding Errors When You Use Floating-Point Numbers