You have the following chart that shows the cumulative of sales from various dates.

[References: https://help.tableau.com/current/pro/desktop/en-us/dates.htm https://help.tableau.com/current/pro/desktop/en-us/dates_continuous.htm https://help.tableau.com/current/pro/desktop/en-us/formatting.htm, , To ensure the dates are shown in a continuous axis, you should convert the date to a continuous field. This will display the months in a sequence without any breaks, which is needed for showing a trend over time like the cumulative sum of sales., ]