Hi

I'm struggling with a new checkout rule I want to implement:

I'm having a content type 'project' with some productvariations (reward1 -€5,reward2 -€10,reward3 -€20)
In this content type there is a 'total_amount' field (initial amount set to 0)

Whenever a client puts an order (only one reward possible), I want the 'total_amount' field updated with the amount of the reward.
I need this value of total orders because anonymous users need to see this amount (crowdfunding site). I don't want to give permission to them to view any orders.

For every order this field needs to be updated.

Is this possible with checkout rules? Or how do I need to get this done?

thx for any help.

Kris