Hi thanks for that.
I am actually looking for the Modulus not 5% as per page 159, 8.4.8 of the manual. (% modulus or remainder. For example, 5 % 4 = 1, 36 % 6=0, 23 % 7 = 2)
So Australian Minimum Bet is $5. So if Balance = 103.50, Balance % 5 would equal 3.50 (so I can add $3.50 on to $5 for a total bet of $8.50)