<?xml version="1.0" encoding="utf-8"?>
<!-- http://blog.flexexamples.com/2007/12/13/rounding-numbers-in-flex-using-the-numberformatter-class/ -->
<mx:Application xmlns:mx="http://www.adobe.com/2006/mxml"
        layout="vertical"
        verticalAlign="middle"
        backgroundColor="white" viewSourceURL="srcview/index.html">

    <mx:Script>
        <![CDATA[
            import mx.collections.ArrayCollection;
            import mx.formatters.NumberBaseRoundType;

            private function button_click(evt:MouseEvent):void {
                textInput.errorString = "";
                numberFormatter.format(textInput.text);
                if (numberFormatter.error) {
                    textInput.errorString = numberFormatter.error;
                }

                arrColl = new ArrayCollection();

                numberFormatter.rounding = NumberBaseRoundType.NEAREST;
                arrColl.addItem({type:numberFormatter.rounding,
                        value:numberFormatter.format(textInput.text)});

                numberFormatter.rounding = NumberBaseRoundType.UP;
                arrColl.addItem({type:numberFormatter.rounding,
                        value:numberFormatter.format(textInput.text)});

                numberFormatter.rounding = NumberBaseRoundType.DOWN;
                arrColl.addItem({type:numberFormatter.rounding,
                        value:numberFormatter.format(textInput.text)});

                numberFormatter.rounding = NumberBaseRoundType.NONE;
                arrColl.addItem({type:numberFormatter.rounding,
                        value:numberFormatter.format(textInput.text)});
            }
        ]]>
    </mx:Script>

    <mx:ArrayCollection id="arrColl" />

    <mx:NumberFormatter id="numberFormatter"
            precision="2"
            rounding="up" />

    <mx:ApplicationControlBar dock="true">
        <mx:Form styleName="plain">
            <mx:FormItem label="number:"
                    direction="horizontal">
                <mx:TextInput id="textInput"
                        text="2.0499"
                        restrict="[0-9.-]"
                        maxChars="6" />
                <mx:Button label="format"
                        click="button_click(event);" />
            </mx:FormItem>
        </mx:Form>
    </mx:ApplicationControlBar>

    <mx:DataGrid id="dataGrid"
            dataProvider="{arrColl}"
            rowCount="4" />

</mx:Application>