Overall, maybe in the range of 1.5-2% (optimistically speaking) as my cards are not very rewarding except for LIT..
I can't waste time further in calculating total cashback, on top of all the mental math that was done at the time of spend to optimize rewards.
Most of the time, I prefer to use the card which has instant discount offers, than worrying about reward points/cashback. RP/cashback is the last resort.
On the same topic, Au has a discover dashboard that shows the lifetime cashback/RP details etc. It was cool.