Also suggest;
- Make an option to include/exclude the tax (GST in this case) in the product price, rather than add it on at checkout.
- Make the tax name and amount appear in the checkout tax row. ie. GST 10% | $50

this is done as of version 1.0.7

Also here in sweden we need taxes in shop!

same in germany: a MUST HAVE (normal products: 19%, books, food: 7% etc.)

Absolutely! In the UK we need to be able to charge VAT for the UK and for EU countries but not for countries outside the EU. For example osCommerce allows products to be defined as taxable or not taxable, and and allows different tax rates to be configured by zone; There's also special cases of provinces where tax rates and customer addresses need consideration, for example the following are part of the UK but have different addresses and some have different VAT rates:

1) Northern Ireland at 20%VAT and is part of UK but 'Northern Ireland' needs to appear in the address.
2) Islands of Guernsey & Jersey at zero rate, Guernsey or Jersey need to appear in the address.
3) Isle of Man at 20% VAT but not part of the UK