In my coffee van business I typically enter a transaction on my Square Terminal and immediately move to the coffee machine while the customer taps to pay. This might happen up to 60+ times per hour so the process is very quick-fire and doesn't allow for alot of extraneous steps, so if one customer's payment is declined I often only see this when process the next customer's payment (by which time the previous customer has departed). Having an audible alarm would provide an immediate alert to a problem and could prevent this occurrence.
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