My product costs £1.25 at full price however at the moment I can places a Category special to discount it by 10%. This the price is now £1.125. This of course includes half a pence which is reflected in the product line totals but actually is then rounded up in the Final Total.
Therefore if I sell 16 units the total for that product is 16 x 1.125 = £18.00; However the Sub-Total is 16 x 1.13 = £18.08
I'm not sure which should be right as you probably shouldn't display a price with a half pence but they should at least match.
See attached image.
Create an item with half pence/cents