The Scotland international netted his 99th and 100th career league goals in either half to give Rovers a 2-0 win at Ewood Park on Saturday.
Blackburn paid £8m for the 22-year-old in the summer, and Appleton believes that it was money well spent by Blackburn.
"Rhodes will net another ton," Appleton told Radio Rovers. "That is why the club paid the money that they did to bring him to the football club.
"We knew what Bristol City would be like, we knew they'd be direct, we knew it wouldn't be pretty. But I don't care how they come, all I'm interested in is results.
"I'm sure Jordan will get another 100 at some point, lets hope it is with us in the Premier League. We're going in the right direction with two clean sheets. Teams aren't fearful of each other, we just have to make sure that we are on our game when we play."
Blackburn now sit 13th in the Championship table.