Tableau Create a running sum by Quarter of year

Question

I have a Rate table that changes Quarter on Quarter.

i.e

+--------+-------+------+
|   Q1   |       |      |
+--------+-------+------+
| Sales  |       | Rate |
| <1000  |       | 1%   |
| >=1001 | <2500 | 2%   |
| >=2501 |       | 3%   |
+--------+-------+------+
|   Q2   |       |      |
+--------+-------+------+ 
| Sales  |       | Rate |
| <1500  |       | 1%   |
| >=1501 | <3000 | 2%   |
| >=3001 |       | 3%   |
+--------+-------+------+

etc..

I have created a Quarter field :

if month([booking_date]) = 1 then 1 
ELSEIF month([booking_date]) = 2 then 1
ELSEIF month([booking_date]) = 3 then 1
ELSEIF month([booking_date]) = 4 then 2
ELSEIF month([booking_date]) = 5 then 2
ELSEIF month([booking_date]) = 6 then 2
ELSEIF month([booking_date]) = 7 then 3
ELSEIF month([booking_date]) = 8 then 3
ELSEIF month([booking_date]) = 9 then 3
ELSEIF month([booking_date]) = 10 then 4
ELSEIF month([booking_date]) = 11 then 4
ELSEIF month([booking_date]) = 12 then 4
END

And tried all types of ways to make the equivalent:

Qtly Cum. Sales

If Quarter = 1 then sum(Sales) elseif Quarter = 2 then sum(sales) etc...

So i would end up with

+-----------------+-----+-----+-------+-------+-----+------+
|                 | Jan | Feb | March | April | May | June |
+-----------------+-----+-----+-------+-------+-----+------+
| Sales           | 200 | 350 | 500   | 400   | 500 | 700  |
| Qtly Cum. Sales | 200 | 550 | 1050  | 400   | 900 | 1600 |
| rate            | 1%  | 1%  | 2%    | 1%    | 1%  | 2%   |
+-----------------+-----+-----+-------+-------+-----+------+

Answer 1

Put your Quarters Field in the columns shelf -- it will partition your months by quarter, but you can hide this header later. Click on your [Sales] pill

1. Quick Table Calculation > Running Total
2. Compute Using > Pane (Across)