LAKOR Soulwear

It works pretty well for us, but it seems I have run into a big hurdle. We use multiple currencies with Shopify Payments. If I set up a volume discount of 30 DKK when purchasing 2 products, it works fine when user has selected DKK as currency. But when he switches to USD, the customer gets a discount of $30, which is 6 times too much. Am I missing something?