Woo Commerce Coupon and Tax

Hello, I have set a coupon for 15% and I had a line item that was confusing to me. See below:

Cost Qty Total Tax
$61.20 1 $61.20 $3.67
-$10.80 $-10.80 $-0.65

the above is an example of one of the line items there are a few other line items.
But using a 6% sales tax and 15% coupon how did it come up with the -$10.80? This is confusing the client and it appears the tax is incorrect because the total PA tax is listed as $3.67 which is the tax on the full amount and not the discounted amount??

Please Help !!

TIA

Jason