Invoice Calculation Weirdness in 1.21

[Luke <..hidden..>]

I am running LSMB 1.21 for this installation.

I have an invoice with a line item as follows:

Qty: 11
Price: 12.90
Disc: 25%
Total: 106.48

Now, that total is wrong.  It should be, assuming banker's rounding, 
106.37.
However, it is consistent with the way LSMB usually does discount 
handling.

It did the same thing with another line item.

Okay, so I know why that is happening, and how to deal with it.

Here's the weird bit.

On the printed version of the invoice, it appears to be doing the correct 
precision three math, and is coming to the correct result.

The customer pre-paid based upon my review of the total on screen, which 
was 152.26.  The total on the page, however, is 152.05.
I didn't look at the line item totals and manually calculate them, until 
after I hung up from taking the payment.

Since the customer prepaid, the printed version of the invoice now shows a 
balance due, of -0.21.

My question is: why is this happening differently on the two versions of 
the invoice?  The on screen version, while not the correct method of 
handling the math, is the way the program usually does it.  The printed 
version, while preferable to the customer, and the correct 3-precision 
handling, is abnormal.

Can this be reproduced, or is it local to my installation?

Luke