Processing fee for square online when item costs $0?

[islamr]

How does the processing fee work for Square online checkout when the item costs $0?

My website offers custom orders which are priced at $0, once a customer places an order I follow up with a Square invoice. Custom orders are in the item library and are available to purchase via Square online check out, like other regular items.

Am I paying the 30cent fee on the $0 when the order is first placed, then paying the processing fee again when the follow-up invoice is paid? Is there a more efficient way to do this?

[JustinC]

There isn't a processing fee on $0 purchases since there's technically nothing to process.

Now, the processing fee applies when your customer pays the invoice you send them with an actual price. 

@islamr