Reporting Services :: SSRS Matrix Aggregate Values And Rounding Error

I am using SSRS 2014. I'm using a matrix instead of a tablix because it allows me to have dynamic columns. In the example I'm showing, two of the columns use the sum function to get the total counts per practice. The third column contains percentages so I averaged for the total but the value is inaccurate compared to the value I would get if the divided the the two totals that are sums of the counts. Is there a way for me to specify that I want to divide the total counts numerator divided by the total counts denominator?

Here's an example report output with the percentage column averaged (inaccurate):

PCP            numerator denominator percentage
John Smith  66             104  63.46
Tom Jones    4                36    11.11
.
.
.
Jane Doe     1    1       100
Total 708          1005       72.3

So the 72.3 value is from Avg(metricvalue)

I would like to do this instead: % total = 708/1005, which equals 70.5 - a significant difference.

The metricvalue column is what is the value for every number above (Because it's a matrix).