Gross Profit calculation in Sales

In usual practice, how the gross profit is calculated if there is a delivery charge applied.
For example,
Without delivery charge,
Item Price = $120
Item Cost = $100
If there is no delivery charge, the gross profit can be calculated as:
Profit = (Price - Cost)/Price 100 = (120-100)/120100 = 20/120*100 = 16.66%

With delivery charge,
Item Price = $120
Item Cost = $100
Delivery Charge = $5
Profit = (Price - Cost - Delivery Charge)/Price 100 = (120-100-5)/120100 = 15/120*100 = 12.5%

Will this Delivery Charge be added to "Item Cost" or will this be treated as other operating expenses ?