CC 5.2.13 (just upgraded from 5.2.12)
I am running a sale, and it may be that Coupon codes are messing up tax calculation (6% PA tax)
Here is a sale from 9/20/2014 (running 5.2.12) and calculated tax fine
note: 6% tax on items and shipping is needed.
Here are two orders where tax was incorrect, where the customer used a coupon code (today 9/27/2014)