While most Singaporeans will understand “Pay cash or credit card”, grammatically it is not a proper question. It can also come across as abrasive.

It may also sound like you are telling the customer about payment options i.e. that he/she can pay by cash or credit card, instead of you trying to find out how the customer will pay for the items.

Avoid Misunderstandings

To ensure your customers understand what you’re saying, and feel that you are giving them options when making a payment, make sure you ask the question politely.

You should say, “Will you be paying for this by cash, NETS or a credit card?”  This will ensure your customer knows that you are asking which method of payment he/she is using.

Source: Edited from the Singapore Retailers Association's Speak Good English pamphlet.