Round moment.js object time to nearest 30 minute interval

I was trying to round the moment.js time object to next nearest 30 minute interval. But looks my logic us wrong.

Ex:

10:13am -> 10:30am
11:45am -> 12:00pm

Here is my current code

start = moment();
minuteReminder = start.minute() % 30;
start.add(minuteReminder, 'minutes');
start.format("D YYYY, h:mm:ss a");

Solution 1:

Edit 2021 : easiest solution

const start = moment('2018-12-08 09:42');
const remainder = 30 - (start.minute() % 30);
 
const dateTime = moment(start).add(remainder, "minutes").format("DD.MM.YYYY, h:mm:ss a");

console.log(dateTime);

<script src="https://cdnjs.cloudflare.com/ajax/libs/moment.js/2.20.1/moment.min.js"></script>

Million ways to do this. You don't need moment.js really. Anyway, here is one.

Solution 2:

Based on @Volune and @Cabloo answers and comments, an updated version can look like:

function round(date, duration, method) {
    return moment(Math[method]((+date) / (+duration)) * (+duration)); 
}

Which then can be used like:

var date = moment();
var roundedDate = round(date, moment.duration(15, "minutes"), "ceil");