- Make sure that product tax class is set to Taxable Goods on product edit page, tab Prices.
- Make sure customer groups are saved with proper customer tax class assigned (Customer > Customer Groups)
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- Rsync newest core into the store. Look at diff between 1.9.3.0 and 1.9.2.4+SUPEE-8788 here: https://gist.github.com/digitalpianism/14a15cd52baede0e5d600e8c653f33e9
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