何过

static Round(value:number, decimalCount:number):number {
        if(value == null)
            return null;

        let precision0 = Math.pow(10,decimalCount);
        let value0 = Fix999(value * precision0);
        let value0x = Fix999(Math.floor(value0) / precision0);

        let precision1 = Math.pow(10,decimalCount+1);
        let value1 = Fix999(value * precision1);
        let value1x = Fix999(Math.floor(value1) / precision1);

        function Fix999(x:number) {
            let s = x.toString();
            if(s.indexOf('.') > 0) {
                if(    s.endWith('99999')
                    || s.endWith('99998')
                    || s.endWith('99997')
                    || s.endWith('99996')
                    || s.endWith('99995')
                    || s.endWith('99994')
                    || s.endWith('99993')
                    || s.endWith('99992')
                    || s.endWith('99991')
                    || s.endWith('99990')
                ) {
                    return parseFloat(x.toFixed(decimalCount+3));
                }
            }

            return x;
        }

        var s1 = value1x.toFixed(decimalCount + 1);
        return s1[s1.length - 1] >= '5' ? parseFloat(Fix999(value0x + 1/Math.pow(10,decimalCount)).toFixed(decimalCount)) : parseFloat(value0x.toFixed(decimalCount));
    }