I don't carry cash, haven't for 6 or 7 years now.
Electronic transaction fees with debit cards are non-existent.
My paycheck goes straight into my bank account.
Transferring money to other NZ bank accounts electronically costs nothing, and shows up within 1 day (or instantly if the same bank).
In fact, the only time I get charged is if I actually use an ATM, or go into the bank to speak to someone.
But there is no merchant in NZ who does not accept electronic transactions, so no need to use an ATM, or carry cash.
Only necessary if you want to transact without knowledge of the revenue department :)