Align A Single Column In Pivot

If the value you want to center is the first column (shown below as Total Cost) -

Give the following script a try:

/*Center aligns first Value column */
widget.on('ready', function(sender, ev){
$('td.p-grand-total-head.p-first-data-col',element).css('text-align','center');
$('td.p-value.p-first-data-col',element).css('text-align','center');
});

For Value columns outside of the first one, it is more challenging to to narrow down on the content but is still do-able.

Use the following script:

/*Center align specified column */
widget.on('ready', function(sender, ev){
$('td[id=pivot__C1]',element).css('text-align','center');
$('td[fidx=3]',element).css('text-align','center')
});

Change the pivot__C1 value to how many Value columns across to align the title text (see image below for example)
Change the fidx=3 to how many columns total across to center the content in that column (see image below for example)