This video shows you how to use woocommerce's built in shipping options including flat rates. The formulas used for flat rates are as follows [qty], [cost] or [fee percent=“10” min_fee=“5” max_fee=“”]
Examples:
[qty]*5 = $5 per item
[cost]*0.1 = 10% of total cost
[fee percent=“10” min_fee=“5” max_fee=“”]= 10% of total cost with a minimum fee of $5