The composite index, which combines the two measures, held at 56.9 on a GDP-weighted basis and edged down 0.3 of a point to 57.2 on a free-weighted basis.
Ebert said the retail trade category had been one of the strongest in the PSI, with a three-month average of 56.5, against 49.2 a year earlier.
"This aligned with the recent trend in electronic card transactions, especially after their reported 1 per cent increase in the month of June.
"The other source of confidence in the retail sector came from the merchants' component of the QSBO [NZIER's Quarterly Survey of Business Opinion]. This, in June, had a reasonably positive view on activity over the coming six months. This suggests retail trade growth, as per the Statistics NZ series, will largely sustain its recent solid pace through calendar 2016."
Three of the five sub-indices improved in June, with supplier deliveries up 2.8 points to 55.2 and stocks/inventories up 1 point to 53.4.
Employment rose 0.4 of a point to 55.1. Activity/sales dropped 2.1 points to 58.1, and new orders/business fell 1.7 points to 58.3.