App Store Connect can show the exact proceeds that you will receive in each region for any price.
For example, if I select a price of 100 EUR for Germany, it shows proceeds of 71.43. That can be explained as 100 / 1.19 = 84.03 (i.e. VAT of 19%), and then 84.03 * 0.85 = 71.43 (i.e. Apple's "small business" commission rate of 15%).
Neither of your examples is correct, because 21% VAT on a VAT-inclusive price of €100 is not €21!
Topic:
App Store Distribution & Marketing
SubTopic:
General