US boxer Floyd Mayweather Jr has been jailed for 90 days by a Las Vegas court after pleading guilty to assaulting his ex-girlfriend, Josie Harris, in 2010.He was also ordered to pay a fine of $2,500 (£1,600) and complete 100 hours of community service.Mayweather, 34, agreed to a plea deal, meaning he will not have to answer felony charges of beating Ms Harris and threatening two of their children.Prosecutors said Mayweather's history meant jail time was appropriate."He just continually gets himself into trouble and he is able to get himself out of it as well," Prosecutor Lisa Luzaich told Judge Melissa Saragosa."Essentially it is because he is who he is and is able to get away with everything. The only thing that's going to get this man's attention is incarceration."Pacquiao boutMayweather has been told to report to jail on 6 January.He is facing another court appearance next week on charges of assaulting a security guard outside his home in November 2010 in an argument over parking tickets. He is expected to plead no contest.His jail sentence means he will be released only two months before a major fight against the Philippines' Manny Pacquiao, scheduled to take place on 5 May.