About all we could suggest along those lines would be having a secret discount code for 100% off the Item Total, so your sales clerk could enter that code in your cart to enable our Free Checkout:
E-junkie is deliberately positioned as a very simple, basic e-commerce service for very simple, basic needs to handle online orders. It may simply be that your needs have outgrown what E-junkie can reasonably do, so if we've become the wrong tool for your job, you may be better served by a more full-featured e-commerce package that includes in-person POS functionality for your physical store.
Right now, Development has their hands full just keeping up with our growth, making improvements to our stability and performance, and working on the long-delayed new Admin project; once the new Admin is ready, we'll be able to tackle implementation of popularly-requested new features and functionality on the wishlist, so rarely-requested features such as adding POS functions would be unlikely to make the cut anytime soon. This post explains our development strategy and constraints in more detail: