WordPress Plugin to collect rent online

[Todd Witt]

Does anyone know of a good WordPress plugin that can be used to collect rent online? I am looking for something with a membership style layout where the tenant will create a user name and password, then I can assign a monthly bill amount to the account. I would also like the option to count the bill as paid as the administrator if they decide to pay offline in a given month.

I am pretty new to WordPress so I may be looking at them wrong, but it looks like all the shopping cart plugins I can find would require the tenant to choose a rent amount to pay. In that case a tenant could "accidentally" choose an amount less than they owe and then argue that I accepted the lessor amount as full rent for that month. I have learned the hard way to never accept partial rent payment.