This is not getting any simpler. According to the Pennsylvania Code:
§ 53.2. Footwear, footwear accessories and footwear repairs.
(a) The sale at retail or use of footwear is not taxable unless the footwear is of the type normally worn for formal, sport or athletic wear. Therefore, ordinary shoes, overshoes, safety shoes and sneakers are not taxable. However, shoes for formal wear, ski boots, bathing shoes, bowling shoes, golf shoes, baseball shoes and football shoes are not exempt from tax.
So in any case, regular sneakers in Pennsylvania are also exempt from Sales Tax.
I'll add this to the total tally of time I have wasted on this.