If you want to group your job costing by phase only at the job level, you can use job folders.
When quoting, make use of job templates to create your quote. On your job template you can create default folders. Save the template header and then add your milestones, tasks and cost, selecting the appropriate default folder for each item.
Then, when you create your quote, all you need to do is select the first phase template and then within the quote choose Options > Apply additional templates.
Otherwise it's not possible to directly group tasks and cost items by phase at the quote stage. Contact us for more advice.