Bumping. Because this needs more eyes and more people calling Shopify to make this feature request. Not just comments on the forum.
Even with the "upgraded" POS, nothing! Perhaps Shopify should have their programmers work retail for a month or more, so they understand why this is an important feature in a POS. Or they could come up with a customer app were customers could check their balances at shopify stores, think of all the extra data collecting they could do