In yet another sign of how Australian banks and consumers are adapting to new technology, Westpac announced on Tuesday that beginning next week, its millions of customers could use the bank's tap-and-go app when shopping.

However, it would only work for bank clients who own the Samsung Galaxy S4 and Galaxy S5 models which come with built-in near field communication (NFC) chips. That would eliminate the need for passwords to make a transaction.

Westpac estimated that by 2015, about 3 million bank customers would use their contactless payment technology to purchase $3 billion worth of products and services.

Westpac Chief Product Officer David Lindberg said that while low value cash transactions would gradually go down because of the app, cash won't disappear entirely. But more Aussies would likely use the app to pay even for their morning coffee, lunch or train pass - which they currently often pay in cash than use their credit cards - eliminating the need for so much cash in wallets.

"Eighteen months ago, we could see the momentum building in contactless payments, the ability to take out your credit or debit card and tap it on a terminal and have the payment go through it. It was about 18 per cent of all scheme debit card transactions in Australia. In the last 12 months we've seen this figure skyrocket to 60 per cent," Mr Lindberg disclosed.

The app would be an option from the current MasterCard PayPass and Visa payWave systems accepted by Aussie shops.

The announcement comes just days before the S5 hits stores on Friday. During the launch of the S5, Samsung said the app would benefit Westpac and Commonwealth Bank customers.

The two banks partnered with the South Korean tech giant for the app use because Apple phones do not have NFC chips.