The reason...
There are multiple sellers in one site.
I was unsuccessful at using the parelle payment gateway via paypal.
So, I'm trying to come up with a solution where a user can only add to the cart the items from distinct seller at a time and then checkout. Each seller payment processed individually.
What I thought would work is that the cart session would end when a user goes to the other seller pages and then could start a new session based on that seller.
Each seller has their own products page (which opens in a new window) there a user can add to cart from that page and go through checkout.
But I have to factor in if a user doesn't checkout, and goes to another sellers page...the cart allows for all "add to cart" items, so I end up with a mix of sellers in the cart. :(
I need to be able to clear the cart if a user goes to a different sellers product page.