Item level tax rates?

Hi Guys

I'm starting to look at tax rate/markup/discount per item in an invoice - just wondering how the different tax system work each each country (as want to be able to handle as many different locales as possible)

If you can post what country your from and how you are supposed to handle different taxes in 1 invoice it would be great

some questions i have are:

  1. if we have multiple tax rates per line items is there still a need for an invoice level tax rate?
  2. how many tax rates are you supposed to have for your line items. ie 1, 2 or 3 - if so detail what they are
  3. if there is a need for an invoice level tax rate (assuming that you can set whatever tax rates per item ) is this invoice level tax calculated inc/ex the line item tax(es)?

hopefully the below example explains that i mean better :)

ie.

id qty product_id unit_price item_tax_1 item_tax_2 invoice_level_tax
1 1 1 $100 10% = $10 5% (is this calc on $100 or $110)? 10% (is this calc on $100 or $115)? - is this tax rate even needed?

also do you guys have a need for just % based rate - or would you also need to handle misc. $ markup/downs per line item?

just post here in the discussion section or in the forum: http://simpleinvoices.org/forum/discussion/672/item-level-tax-rates/ Cheers

Justin