Captain Ross Taylor reached 36 and opener Martin Guptill contributed 32 in an unbroken third wicket stand of 63.
After the hosts won the toss, Roach found the edge of both openers' bat before B.J. Watling (2) edged straight to Chris Gayle at first slip at 10-1. The delivery was close to being a no ball but third umpire Richard Kettleborough confirmed the dismissal after viewing TV replays.
One run later, Best got into the act as Brendon McCullum (0) edged to wicket-keeper Denesh Ramdin after being squared up by one that seamed away.
Best, who replaced the injured Ravi Rampaul, almost had Taylor first ball, a nasty lifter that was fended just out of the reach of gully.
However, Taylor blossomed in the second hour, slamming five fours off 68 deliveries.
Guptill hit two fours and a six off 80 balls.
New Zealand made three changes to the team that lost the first of the two-test series in Antigua by nine wickets last Sunday. Daniel Flynn and Daniel Vettori were ruled out due to groin injuries while Chris Martin was dropped.
Watling, Tim Southee and Trent Boult were the replacements.