The rolling window variable will accumulate the values received on the variable selecting every time you setted, in this case it will accumulate the values every one minute.
As you can see on the images below, I'm sending the variable "test = 2" every second to Ubidots.
I created two rolling window variables to verify that the result is okay. First, I created a rolling window variable to sum the values received at "test", and another to count every data point received during one minute.
As you can see the count-test variable received 53 data points during the minute:
So, the sum-test variable accumulate the sum of the 53 data point received, thats mean if the test value is equal to 2 the accumulated value will be 106
As you can see I made the test and everything works fine! To get a better a idea how the variables works, take a look of this video.