Show total of cart variants

[Zegenrijk]

I want to show on the productdetail page the total of cart variants, clients choose (or not).

Normal sales price: 100
Color: red + 15
Size: small + 10

Normally VM counts this in the salesprice, so this shows automaticly 125 (100+15+10) and recalculate when changing an option.

On the screen i want to see also the total of the cart variants 25 (=15+20). How to count and show the total of the cart variants?

Regards Michel