编辑2 ：

使用 Number 对象的 toFixed 方法，如下所示：

Use the Number object's toFixed method like this:

var num = Number(0.005) // The Number() only visualizes the type and is not needed
var roundedString = num.toFixed(2);
var rounded = Number(roudedString); // toFixed() returns a string (often suitable for printing already)

它将42.0054321舍入为42.01

It rounds 42.0054321 to 42.01

它向下舍入0.005到0.01

It rounds 0.005 to 0.01

它将-0.005舍入到-0.01（所以在舍入时绝对值会增加.5边框）

It rounds -0.005 to -0.01 (So the absolute value increases on rounding at .5 border)

jsFiddle示例