change the Total Price calcualtion:
(abs([Size] == '2XL' || [Size] == '3XL' || [Size] == '4XL' || [Size] == '5XL' || [Size] == 'XL'))?[Price] + 3:[Price] * [Quantity](abs([Size] == '2XL' || [Size] == '3XL' || [Size] == '4XL' || [Size] == '5XL' || [Size] == 'XL'))?[Price] + 3:[Price] * [Quantity](abs([Size] == '2XL' || [Size] == '3XL' || [Size] == '4XL' || [Size] == '5XL' || [Size] == 'XL'))?[Price] + 3:[Price] * [Quantity]
to:
((abs([Size] == '2XL' || [Size] == '3XL' || [Size] == '4XL' || [Size] == '5XL' || [Size] == 'XL'))?[Price] + 3:[Price]) * [Quantity]
if you continue to have a problem, include a link where i can see the problem with your reply