Jennings was fined for the timing of his post, not the content, when he tweeted: "Back to 500. Yess!!! '500' means where doing good. Way to Play Hard Guys."
On Friday, Jennings posted: "I understand I got fined, but 7500? For being happy over a win, you would of thought I said something bad. I mean it was a big win for us."
The fine was announced Friday before the Bucks played at Cleveland.
"I'm bout to delete my twitter," another Jennings posting said. "Twitter cost me 7500. Looks like no Gucci and Louie for Xmas."
When asked about the fine before Friday's game, Jennings admitted he made a rookie mistake.
"It was a lessson learned and I'll move on from it," he said. "Don't Tweet when you're in the arena. I won't do that anymore. That's a lot of money, especially around Christmas time. You do a lot of shopping for the family. It doesn't look like I'll be able to do that this year. I may just have to give out a bunch of Under Armour gear."
According to the NBA's social media policy, players cannot tweet during game time, defined as beginning 45 minutes before the game starts and ending after players have finished talking to the media following the game.
The message for which he was fined has been removed from Jennings' account.
Information from The Associated Press was used in this report.