How do I alter prices?
Figured it out:

function comply_advantage_uc_cart_alter(&amp;$items)
{
    $item-&gt;price-&gt;setValue($item-&gt;price-&gt;value * 0.95);
}


Hope it helps someone!

** IMPORTANT **

It looks like if you use 

$item-&gt;price-&gt;setValue($item-&gt;price-&gt;value * 0.95);


Yo might end up altering the price several times. So I had to actual recalculate the price completely, without using $item->price->value, or it would deduct 5% multiple times.