Formula to calculate percentage based on date and Value

I am trying to find an easy way to calculate super based on date and totals
In a Month if the total Gross exceeds $ 490 then 9.5% applies to each figure
If $ 490 is not reached [total] then the 9.5% does not apply
What I am seeking is that the formula looks at the total for the month and if it exceeds $ 490 then it calculates

I have attached an example sheet

Assistance appreciated