A try from Munster scrum-half Conor Murray and a conversion and a penalty from Leinster fly-half Sexton did the damage but the lead wasn't too last long.
Four penalties thereon in from Carter plus a converted Aaron Smith try put the Kiwis 19-13 ahead although two penalties from Sexton to add to one at the start of the second half pulled Ireland level.
However Carter broke Irish hearts as they fell 22-19 to surrender the series while Mike Harris' injury-time penalty crushed Welsh ones as Australia recorded a 25-23 victory.
Wales looked set for their first win over the Wallabies in Australia for 43 years as converted tries from George North and Jonathan Davies plus three Leigh Halfpenny penalties had them 23-22 ahead with 14 minutes remaining.
However replacement Harris won it for Australia - who kept themselves within touching distance with a converted Rob Horne try and five penalties from the boot of Berrick Barnes.
Scotland were the only Home Nations outfit to record victory on Saturday as two tries from Tim Visser helped them run out 37-25 winners in a hard-fought contest with Fiji.
Visser's first try at the end of the first half plus a penalty try and 14 points from Edinburgh teammate Greig Laidlaw put Scotland 24-11 ahead at half-time.
However tries from Waisea Nayacalevu and Metuisela Talebula, to add to Josefa Domolailai's first-half score, helped cut the deficit to two points with 12 minutes to play.
However Visser had the last laugh, grabbing his second try in the 72nd with Laidlaw converting to end with a personal tally of 22 points.
63x46.png){kind=logo}