As a business owner, it’s not feel complete yet while you sell your product/service without giving receipt to your customer with thermal printer.
Besides it’s very useful to easier refund transaction proccess of your customer’s purchase, it will make your store management neater and more beautiful. You could also use logo of your store on receipt as indirect marketing.
iREAP POS PRO support with all of kind thermal printer which you can find it easily on online store/e-commerce. You could check iREAP POS PRO supported thermal printer HERE