At a first glance, the template responsible for this seems to be customer/product/details/parts/common.price.twig which looks like
Code:
{{ widget('\\XLite\\View\\Price', product=this.product) }}
It is a bit of surprise that the VAT/GST module isn't directly involved. I don't know if I haven't looked at right place. Hopefully someone more knowledgeble can dig into this.