A withdrawal is the amount taken out of your funding source as a contribution towards your debt. Withdrawals come out in increments of $5+

Once your roundups have reached a total of $5 or more, a withdrawal will initiate. You will get a notification of the withdrawal being initiated, which will allow you to cancel or reschedule before the cutoff time (5:45 PM EST). 

Withdrawals are collected in your Qoins balance for the associated Upcoming Payment Account until the scheduled payment is sent out for the full amount.