Storm Aura damage calculator

Hey I'm currently playing a Storm Herald Barbarian in my campaign. I currently have my Storm Aura (sea) set up as a n Attack that deals 1d6 Lightning Damage with a Dexterity saving throw, this damage increases to 2d6 at level 10, 3d6 at 15 and 4d6 at 20. Now i could just manually change it at these breakpoints but i wonder if there is a formula to make it roll the correct dice automatically. 

something like: [[ ((@{level}/5)+.4)d6 ]]

This worked but is there anyway to make the output not so werid. When i look at the roll in chat it just shows the number it rolled. it just says rolling 4 damage or rolling 3 damage. If i take the [[ ]] out it should the ((5/5)+.4)d6, is there any way for it do display how many d6 its rolling clearly?

[[ [[((@{level}/5)+.4)]]d6 ]]

That did not work it only outputs 1.4

Ahh, then you want to use the ceiling function [[ [[ceil((@{level}/5))]]d6 ]]

This worked perfectly, taking out the outside braces. SO now it outputs Rolling 3d6 = (1, 5, 6) etc instead of just rolling it as 12 = 12 Thanks for your help guys.