Develop a POINT OF SALE software for non-profit org

Need a develop a very simple POS software system (web interface) to accept DONATION PAYMENTS (only) via cash, eftpos and cheque payments, and have the data/transactions record linked up to XERO (our existing accounting software) and our merchant facility. Most of the POS system out there such as SquareUp, Reckon POS has too many features that we don't need. Features we need for the POS software are as follow: - Only need a few items to select from when processing donations (don't need inventory type of items). - Each item need to be linked to different bank account. - Would like each donation to be recorded the bank account as each transaction, not as a lump sum for each day. - Able to generate report for each day and automatically filter the data/transactions to XERO without double entry or manual entry. - Able to import or export CSV file in and out of the software (for example, donor files and records) or able to link donor files directly from our existing client portal. We want to able to upload donor's details on to the receipt when processing the donation. - Employee access and restriction function. - Able to print, email and sms receipt to donors. - Receipt need to have basic customization functions, such as adding logo, business details, donor details, certain note or message. - A standalone application (if possible) so other related centers within our organisation can use them and link it up to their accounting software and POS. Please ignore the price, you advise me how much you think it will cost to develop and I will compare our proposal with others. Look forward to your quote and feedback. Thank you.