in the cart object, create a new calculation called realPrice, my example of the code to use for the realPrice calculation is based on a column named "Name" (including case), if your is different, you'll need to adjust it accordingly:
abs([Name] != '')?[Price] + 3.25:[Price]
then modify the Total Price calculation from:
[Price] * [Quantity]
(abs([Name] != '')?[Price] + 3.25:[Price]) * [Quantity]
int he cart display, you will need to change that code that displays the price to use the new realPrice calculation instead. this will also need to be changed in the code that sends the order to the gateway and in the store order details behavior.