Shipping, add $1.00 for each additional item in the cart

Hello! I have a general inquiry, quick fix, etc.

I have a client that wishes to add $1.00 to the total shipping for every additional item in the cart. If flat rate shipping is $5.00, and someone adds 3 items to the cart, the new shipping total should be $7.00.

Is this possible? Is there a simple solution we can install for this? We are comfortable editing code to place in whatever you need. Let us know.