One share cost: $26.25.
Sam wants to buy 100, which means that the total price of the shares is:
100*$26.25=$2625.
There is also commission of 5% of the total amount:
5% of $2625, which is:
(5/100)*$2625=0.05*$2625=$131.25
So, Sam's total cost will be: the total price of the shares + the commission
$2625+$131.25=$2756.25