When you've got expenses you need your client to reimburse you for, you can create an expense/reimbursable proposal. To do this you would create a new proposal, and then in the Products panel that appears on the right side of the screen, click "Project Drafts" from the top right, then choose "All Services" in the dropdown menu that appears. Click "+ Add New Service" from the bottom left corner of the panel.

Add the service title (e.g. "Parking"), and choose "Expense" as the category. Input the details of the reimbursable charge and save it in the panel. This will add the reimbursable item (expense) as a line item to the proposal. 

You can do this for each reimbursable item you have and keep an ongoing, open proposal which you continue to add to throughout the project if you'd like. You can even upload to each line item a JPEG image file of any receipts you have.
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When you're ready to bill your client for all of these reimbursables, convert the proposal into an invoice and send them the invoice for payment.