I have figured it out! Maybe my rants on here helped. 

I have used the custom scoring and made all of the 1st attempts to each of the questions worth 0 points alround, and the last question in the bank worth 5 points.

If the user gets them all correct they score 5/5 = 100%

If they get the second attempt correct they still score 5/5 = 100% because the 1st attempt was worth 0. 

If they get both wrong, they score 0/5 exactly how we need it :)