The 26-year-old is out of contract in the summer and Everton are thought to be leading the race to secure his signature - but Grayson is happy for his striker to raise his profile further as it will mean success in getting out of League One or progressing in the cup.
Grayson is also unwilling to sell his striker during the current transfer window.
"It would have to be a lot of money because we have turned down decent money already for him," he said. "Jermaine wants to stay and finish the job off.
"If someone comes in with ridiculous money - and I'm talking a lot more than £2million - then we'd look at it again. But I've got no intention of selling him in the window because it's too late to get a replacement and he's too valuable to lose.
"I have said all along I would rather Jermaine leave on a free and I wish him well because hopefully in that meantime he's got us promoted.
"Jermaine can only win because if he scores 15 to 20 goals until the end of the season he will be linked with bigger clubs than he's being linked with now."
Grayson will also make an attempt to retain the striker, who prodded home to equalise after Peter Crouch's opener, then cancelled out Roman Pavlyuchenko's strike by earning a penalty in the 95th minute which he converted.
"There's still an opportunity he might stay beyond the summer," added the Leeds boss.
"There have been a lot of twists and turns already. He put a request in after the Manchester United game and has come off the list now. He can leave in the summer if that's his choice."
The other hero for Leeds was goalkeeper Casper Ankergren, who saved Jermain Defoe's penalty in the first half.
The Dane played down the plaudits, saying: "I don't think too much, I just try to guess.
"You have to guess, you have to be lucky. You have to do the right thing, look at him, and I was lucky and I saved the penalty."
Alan Wiley's decision to award Leeds a penalty appeared to be debatable, although Spurs boss Harry Redknapp said: "It could have been a penalty. It was a tight one. I wouldn't argue with the referee. He's made an honest decision. Sometimes you get them and sometimes you don't.
"Michael took a chance and tried to win the ball. He did get a foot on the ball."
Pavlyuchenko, who wanted to leave Spurs, seized his rare chance when he came off the bench to score.
Redknapp added: "Pav is here, he's part of the squad and if he plays like he did when he came on every week he will be in the team every week. There's nothing in the offing."
FA Cup. Click here to bet.