Satchmo does not send pricing for subscription products to paypal correctly.
Satchmo sends pricing of five precision points to PayPal when sending subscription subtype (reoccurring) products. This will cause PayPal to display an error to the user that the input was invalid. The PayPal module needs to be updated in order to remove precision greater than 2 from pricing that is sent to Paypal.
I have attached a fix for at least the main price that subscription product subtype use. This may not be the correct way to fix the bug, as I'm sure some currencies use precision greater than 2 in paypal, etc. But it does work for US billing until a proper fix is made.
Reported by nosforz