Just came back into this thread after a notification. After some messing around with IFTTT, @swok1080 and I discovered that sharing a link to a self published Applet works even if you don’t have a developer account.
I tried to put @stugreenham’s code above into a new applet - the link is below.
So if anyone does want 2x Round Up - this should do it:
In theory you could do X% of purchase coin jar, or any multiplier of the round up. Be interested to see if this works?