Calculated field for total value (currency) of entries based on a date field for each month

I’m trying to get a calculation field to show and struggling with formula.

I have a date field and a number field, these represent a renewal date and a renewal cost.

I’m trying to get an additional field that will show total values for all entries within a set period.

The value I’m trying to get to is to show a value for January, February, March etc. with a total for every renewal in that particular month.

Can anyone point me in a direction as really struggling with this.