A running total adds everything up to the current row. For dates, take all dates up to the last date in the row:
Running Total =
CALCULATE([Total Sales],
FILTER(ALL('Date'[Date]), 'Date'[Date] <= MAX('Date'[Date])))
ALL removes the row's date filter, FILTER keeps the dates up to the row's last date, and CALCULATE sums them. Because Date is marked as a date table, the filter on Date[Date] also clears the Year and Month filters from the row.
DATESBETWEEN(Dates, Start, End) does the same with a fixed start, such as January 1, 2025.
ALLSELECTED removes only the filters from inside the visual and keeps the slicers. Use it when the running total should start at the first date the reader selected, not at the first date in the data. And remember distinct counts: a running number of customers must be recounted over the whole period, not added up month by month.