Wouldn't you need personal data to accept payments? Or maybe a broker (like Stripe) would store these and the end business just a reference to payment.
You can get external ref to payment providers. Depending on the business you might need KYC and anti laundering procedures and then it's harder.
However if you have some direct business and do accept payments - by all means make it secure and transparent to your customers.
I work in a place that would be beyond heavily affected by GDPR and I find the legislation a good change as companies should not hoard data they don't need - just in case... or just to sell.