At the beginning of this month New Zealand changed its tax laws to require overseas sellers to collect its 15% goods and services tax on all good s sold over the internet, including ebooks. It's not clear how NZ will get sellers with no presence in NZ to comply, but Amazon has already announced that would collect the tax on schedule.
About two weeks back Amazon announced the change in policy in the KDP support forums:
Starting October 1, 2016, e-books sold to customers in New Zealand will be subject to a 15% New Zealand Goods and Services Tax (GST). This change will affect the prices New Zealand customers see on the Amazon.com and Amazon.com.au websites.
As a result, from October 1, 2016, Amazon will begin collecting and remitting GST for sales to customers in New Zealand. When calculating royalties for sales to customers in New Zealand, we will use the tax-exclusive list prices you provide to us for Amazon.com and Amazon.com.au.
I haven't found evidence to suggest that Apple and Kobo have also complied with the new tax law, but all three did comply when Japan made a similar change to its tax laws last year. So it is highly probable that they are all collecting the GST on behalf of New Zealand.
image by T?kuta