Minimum quantity surcharge via dynamic Rules

Hello, I'm currently trying to create a minimum quantity surcharge for B2B customers.
I'm trying to implement the following via dynamic rules:
“For every order under 100 euros, a small quantity surcharge of 10 euros should be added.”
I have it via the rule type "Tax/Fee", but if I put 2 products in the shopping cart, for example 5 euros, it always calculates the set minimum quantity surcharge for each quantity. So if there are 3 items in the shopping cart for 5 euros, the surcharge of 10 euros is calculated a total of 3 times. How can I set it so that if the value of the goods is less than 100 euros, 10 euros are only added once to the shopping cart, regardless of how many products are in the shopping cart?

Hello Stefan,

thank you very much for your help. Now it works perfectly.