Equation Issue?

My client noticed a minor math issue and I wanted to get a little help if possible. We have a product with a base price of $53.11. When ordering 26 or more we give a 10% discount. My customer noticed a very slight discrepancy when testing a large quantity. When ordering 65 the calculated total after the discount is applied is $3,106.94. Another example – a product with a base price of $2.41 and a quantity of 560 after the 10% volume discount is calculated as $1,214.64. Unfortunately both of these calculations are incorrect because the calculation is being performed as follows:

((unit price * quantity) * (100 – discount percentage))

when, based on the way prices are displayed, the equation should be:

(((unit price * (100-discount percentage)) * quantity)

Given the unit price is shown as discounted, my customer performed the second calculation. For the first example, the correct total should be $3,107 instead of $3,106.94. For the second example, the correct total should be $1,215.20 instead of $1,214.64. While these are minor discrepancies they have cast doubt on the integrity of my customer’s eCommerce website.

What’s your take on this? Thanks, and I am happy to provide you with any additional information you require.