Using IG on metetrader 4. Margin Question

I just started my demo account with IG using $10,000 USD. I placed a sell position with 8 mini lots of GPB/USD at 1.29976. IGs site says margin required is 5% for this pair. Doing the math, a margin of $520 should be set aside from account. However I see $5.20? Why is that. What am I not understanding?

Thanks