This would require custom coding. You should set a variable, then add the values to the variable, then you can display the variable on the page where you would like to see the info.
<%
Session("your_var") = 0
Session("your_var") = Session("your_var") + WA_eCart_GetRuleValueByName(dmbp, "Discounts", URLDecode("VD260Q50to99"))
Session("your_var") = Session("your_var") + WA_eCart_GetRuleValueByName(dmbp, "Discounts", URLDecode("VD260Q100plus"))
Response.Write(Session("your_var"))
%>
This is just an example of how you could do something like this, your code will need to be customized to fit your needs.