An app for a small retail shop to run on the ipad/iphone

Sales/Purchases/Inventory/Refund App on ipad/iphone - A programme for a small single outlet retail firm - Should be able to be installed on an ipad , probably as an app - able to capture inventory,purchases,sales and print out till-sized receipts - Process returns and refunds from customers and to suppliers -process VAT correctly ( to be used in the UK) - able to print from a small mobile printer through the ios airprint or similar device