Accounting Ideas

All our prices include vat. It is very annoying to have to manually work out the price excluding vat to add to an invoice (i know you can do it by creating a new product but that does not always make sense). Also if I want to give someone a discount, say £10, I then have to work out what that is excluding vat. Then the customer will come back and say "I only got £8.33 discount, you said I would get £10".

Also sometimes when you add several products the price don't add up when including the vat. It may only be a few pennies off but it seems strange.