Quickbooks Online supports the concept of marking an invoice line item as billable and specifying the customer to bill. In QBO, invoice line items marked as billable to a customer can also (if QBO is configured that way) have a markup applied so that when the customer is billed for the expense, they pay the original cost plus a percentage markup.

The same concept happens in Beanworks. Once set up, markups are automatically applied for invoices created from Beanworks that have billable selected in the line items. This cost is calculated for the item based on the markup percentage that was defined in Quickbooks for the item as well as the sales price. If you choose to code with an account instead of an item then the default company markup will be applied.

Accounts will take the default markup from the QBO Company, and items will take the specific item markup. It will apply to anything with a line item using the billable flag and calculate the sales amount.

If the sales price isn't available in QBO the markup rate then becomes 0%. 

To find out how to turn on billable expenses in Quickbooks, see this tutorial here