Yet when it mattered most the tourists were woeful, handing the urn over after shocking collapses at Edgbaston and Trent Bridge.
"You look at the end column - the one you want to be ahead in and we are," England keeper Buttler said.
"We've won the Ashes and whether you score 0 or 100, that's a pretty good feeling.
"It's disappointing the way we've played here.
"But, as I said, we have won the Ashes and nobody can take that way from us, no matter how badly we play in this game."
Cook implored his teammates to be ruthless in the dead rubber, highlighting the way Australia never took their foot off the throat in winning the past series 5-0.
Buttler conceded his side may not have been mentally up for the contest, having already taken an unassailable 3-1 lead in the five-test series.
"We spoke about the fact we wanted to try and win 4-1, maybe we got a bit caught up with that as opposed to actually focusing on what we've done well," he said.
Opener Adam Lyth capped a miserable series with a score of 10.
Lyth has scored 115 runs at an average of 12.77 and will almost certainly be axed for England's next test series against Pakistan.
Buttler, who will resume day four on 33, was critical of himself.
"I've had a really poor series," he said.
- AAP
