Avon Products Inc. said Wednesday its third quarter profit jumped 29 percent on slightly higher sales of its beauty goods. Avon earned $44.6 million, or 63 cents a share, in the three months ended Sept. 30 compared to $34.6 million, 46 cents a share, a year earlier., Sales rose 5.9 percent to $830.8 million from $785.1 million in the same quarter of 1989. For the first nine months of 1990, Avon's profit rose 34 percent to $107.3 million, $1.42 a share, compared with $80.3 million, 97 cents a share, a year ago. Nine-month sales jumped 3 percent to $2.33 billion from $2.27 billion in 1989. ``Our strong third quarter reflects continued profit improvements in the U.S. and the Americas, continued reduction in interest expense and a lower tax rate,'' said James E. President, president and chief executive officer of the New York-based company. Third-quarter sales in the company's international unit jumped 8 percent while those for Avon's domestic unit rose 2 percent. The company cut its debt during the quarter to $603.3 million, down from $1.09 billion at the same time last year and $838.1 million at the end of 1989. Avon is trying to sell half of its 60 percent interest in its Japanese subsidiary and should know soon if the transaction can be completed this year, Preston said.