We are selling fabric that is cut to length. There is a discrepancy between in the Sub-Total of the Items as they are displayed to the customer (2 decimal places) and the Sub-Total that is calculated using 4 decimal places. Here is the contents of an Invoice:

Products Model Tax Price (ex) Price (inc) Total (ex) Total (inc)
0.5 x Random Pencil Check in Linen CX4840-LINE-D 6% $9.75 $9.75 $4.88 $4.88
0.5 x Medium Cream Dot in Aqua C630-20-AQUA 6% $9.75 $9.75 $4.88 $4.88
0.5 x Medium Cream Dot in Gray C630-40-GRAY 6% $9.75 $9.75 $4.88 $4.88
0.5 x Small Cream Dot in Gray C610-40 GRAY 6% $9.75 $9.75 $4.88 $4.88
0.5 x Small Cream Dot in Orange C610-20 ORAN 6% $9.75 $9.75 $4.88 $4.88
0.5 x Ta Dot in Lime CX1492-LIME-D 6% $9.75 $9.75 $4.88 $4.88
0.5 x Ta Dot in Sea CX1492-SEAX-D 6% $9.75 $9.75 $4.88 $4.88
0.5 x Medium Cream Dot in Navy C630-21-NAVY 6% $9.75 $9.75 $4.88 $4.88
0.5 x Boy Triangles in Aqua C3305-AQUA 6% $9.75 $9.75 $4.88 $4.88
Sub-Total: $43.88
Zone Rates (Shipping to US): $5.50
PA Sales Tax: $2.96
Total: $52.34

Nine products were ordered, .5 yard of each.
Using the price for each displayed to the customer: 9 * 4.88 = 43.92
Using the price calculated under the hood: 9 * (.5 * 9.75) = 43.875

I've been looking at other threads concerning rounding with discounts and taxes, but I have not seen any involving fractional quantities. I understand that in the database and in the code prices are stored to 4 decimal places. But, the invoice only displays 2, if someone adds it up it doesn't add up.