It doesn't make any difference.
It was stated on the forum many years ago by a "rep" for RTG's software company (Dogboy), that the chance of triggering the RJ on most of their slots is 1 in 300,000 worth of bets.
So if you're betting $1 - your chances are 1 in every 300,000 spins.
If you're betting 20c, it would be 5x harder to hit = 1 in 1,500,000 spins
And if you are a high-roller betting $5 per spin, it would be 1 in 60,000.
Whatever you bet - it's still a long-shot and IMO it is a folly to "chase" any sort of progressive jackpot.
I have read of players winning 2 or 3 RTG RJ's in a single week - and others have NEVER hit one in 10+ years.
I would just play the games you enjoy and just hope that one day you might just get lucky...
KK