The problem is with all items/lines. Nothing seems to change if I tick 'that box'. Im using a 20% tax/vat rate. I have three colomns on the invoice; for each line, I have a unit/item cost, then the tax amount then a total amount. As it stands, both the unit value and total value's are exactly the same which is nuts! However, the final total at the bottom is caluclated correctly showing the sub total amount, then the total tax amount followed by the two figures together as a final total.