Here is the scenario. 
1.  A supplier sell products to me and charge the following taxes:
     a.    Essential goods, 2% tax applies.
     b.    Normal goods:   5%
2.  When I sell these products I will apply the same tax rates on these goods.
3.  I setup tax type:
     a.   Supp Tax Essential goods:  2%
     b.   Supp Tax Normal goods:  5%
     c.   SalesTax Essential goods:  2%
     d.   Sales Tax Normal goods:  5%
4.  I setup tax groups for:
     a.  Supplier:  Supp Tax Essential + supp Tax Normal
     b.  Sales: Sales Tax Essential + Sales Tax Normal
5.  I setup Tax Item Exemption:
     a.   Essential:  Exempt Normal Tax
     b.   Normal:  Exempt Essential Tax
6.  I setup items:
     a.   Essential Goods:  Item tax type: Select 5a.
     b.   Normal Goods:  Item tax type: Select 5b.

With the setup, you could buy the goods and sell them after you add the profit margin.  And the GL etc should be recorded correctly.
This setup works for me to meet my needs and I hope it helps.

/Mark

The supplier is still the same, but when registering the purchase order, he only calculates 7% for me, and he should really charge me the tax according to the type of item to buy.

In the sale the same thing will happen, that is to say that when I sell those articles, I must sell them in the same way, charging my clients the same tax, on the same articles.

And that I did not manage to do, and I have tried several options, I do not know if creating a tax group, the issue is that if I core it, it will charge me the tax, in equal parts, but in my country throughout the territory it charges the same general tax.

Excelente.

Thank you.

https://we.tl/t-6vhJ1M4ry6

1. Created two item tax types one with tax and another with fully exempt.

2. And I already had two taxes 5% and 7%..
3. Then I created two items one with taxed item and another fully exempted item.
4. Then I created a supplier with taxed group. That was also already existing.
5. Now I have gone to supplier invoice and added taxed item with created tax rate. And then I added fully exempted item. There it didn't change the tax value.

Hope this test explains the tax can be applied based on items and suppliers tax group.

Suppose if your supplier is fully exempted tax group. Than it won't apply any tax for his invoices.

On the same supplier invoice, I buy the iPad, and the calculator, but FA does not calculate tax for me, both take them exempt.

Set in SUPPLIER TAX GROUP, I put 7%, and in the articles, I also put 7%, and Excento the one that has no tax.

I think I did that, well, I will reread the help to see if I am doing something wrong, it also provides it by creating a tax group, but I think that does not apply.