Help with creating a formula that will help me to get cumulative Totals

Here's how I would do it. Your dates in the first 3 cells were wrong, so I corrected those. Then I added reference data above the Weekly totals section so the formula in C23 can do a simple SUMIFS().

=SUMIFS($C5:$KY5, $C$3:$KY$3, ">=" & C$20, $C$3:$KY$3, "<=" & C$21)

That is copied down and across... totals appear.

Repeat that technique for your "monthly" section, just provide the start/end dates to the SUMIFS() for what you consider to be months.