in the copy of the cart you sent,
XL is included in the calculation for truePrice:
(abs([Size] == '2XL' || [Size] == '3XL' || [Size] == '4XL' || [Size] == '5XL' || [Size] == 'XL'))?[Price] + 3:[Price]
change that to:
(abs([Size] == '2XL' || [Size] == '3XL' || [Size] == '4XL' || [Size] == '5XL'))?[Price] + 3:[Price]
and set the total price calculation to:
((abs([Size] == '2XL' || [Size] == '3XL' || [Size] == '4XL' || [Size] == '5XL'))?[Price] + 3:[Price]) * [Quntity]