How to create a step graph?

Micha?, you will not be able to achieve the same exact replica in Appian. In Excel, the x axis numbers are treated as continuous. In Appian, each category (100, 101, 200, 201, etc.) is discrete from one another and as you probably have noticed, it does not look good.
Moreover, I think that a bar chart is actually better. It achieves the desired result (convey the breakdown of discount levels based on sales) but it also clearly shows the sales numbers per discount level. In your screenshot, without the table on the side, I cannot really tell where the next steps starts (101 or maybe 102?).

Micha?, you will not be able to achieve the same exact replica in Appian. In Excel, the x axis numbers are treated as continuous. In Appian, each category (100, 101, 200, 201, etc.) is discrete from one another and as you probably have noticed, it does not look good.
Moreover, I think that a bar chart is actually better. It achieves the desired result (convey the breakdown of discount levels based on sales) but it also clearly shows the sales numbers per discount level. In your screenshot, without the table on the side, I cannot really tell where the next steps starts (101 or maybe 102?).