Edit in JSFiddle

var data = [];
data.push({
    id: 1,
    amount: 99999.12
});
data.push({
    id: 2,
    amount: 99999.10
});

var grid = new wijmo.grid.FlexGrid('#FlexGrid');
grid.itemsSource = data;

grid.columns[1].width = 200;
grid.columns[1].format = 'N2';

<div id="FlexGrid"></div>