All your 5 forms are on the same page, will have the same ID, and submit to the same controller action. So, the first will work, and clicking submit on all others will just submit the first form (ie, the others won't work).
First and foremost, I'd get it working as one big fat long form, without tabs - just so you're dealing with one problem at a time. Once that's working, you've got a few options for splitting your form into tabs. The most straight forward is this:
Open your form before the beginning of the tabs, and close it after the end of the tabs. The submit button will lie outside the tabs, below. But the fields themselves can be distributed amongst the tabs as you see fit.
Users will be able to go from tab to tab, editing fields, then save all fields by clicking the submit button outside of the tabs, below.
So that'd look like this:
<?php echo $this->Form->create('Quote'); ?>
<div id="tabs-1">
// A bunch of form fields go here
</div>
<div id="tabs-2">
// A bunch of other form fields go here, etc
</div>
<?php echo $this->Form->end(__('Submit')); ?>
Your other options would be to make each tab a separate form that submits to a separate controller action, and / or use ajax. But the previous way I described should be easiest.