[only confirmed for 4.6] Total tax amount on invoice PDF should not depend on calculation producing incorrect results.

Hello,

Testing out the 4.6 I noticed that the tax rate displayed on invoice PDFs can be wildly inaccurate.

I created a "Loot bag" price set item for an event with 10% (GST) tax rate that was $15 ($13.64 before tax)
Created an event registration that had 5 of these, and I got a line item like:

Loot Bags, Qty: 5, Unit price: $13.64, Amount: $68.20, GST: $6.80

Which is correct assuming the tax rate is applied (and rounded) per unit.

This however produces back a tax rate of 9.97% for the order total, as it's calculated based on the final figure for the line items - when the actual tax rate is 10% and should be reflected as such in the invoice.

Perhaps the tax rate could be saved with the line item?