$(document).ready(function() {
    $('div.shipping input[type=radio]').change(function() {
        var label = $('label[for=' + $(this).attr('id') + ']').text();

        var regex = new RegExp('.*?\\((\\d+)\\s+.*',['i']);
        var matches = regex.exec(label);
        var shipping = parseInt(matches[1]);

        var totalSum = parseInt($('span#totalSum').text());

        $('span.totalSumShipping').text(totalSum+shipping + ',- Kč');
    });
});