Having travelled in China, I can confirm this fact.
I took a cab to the Bank of China in Tianjin to use their Maestro-aware ATMs one day and found found it closed for lunch. Being otherwise pennyless and having nothing else to do I sat outside the bank and chatted with the Blackmarket moneychangers until it reopened. They didn't speak any appreciable English and my Mandarin was limited but to pass the time they taught me to count with the above number system. Once you are a little proficient with it, you can rapidly barter for anything using one hand which is the real point. Being money changers, they lived by this system and probably enjoyed tourists being able to barter for currency too (don't change money with these guys though, you end up either being skillfully short-changed or with counterfeit currency.
The numbers 1-5 are the same as English/American styles, the numbers 6-10 are as above except that I was taught to use the crossed forefinger/index finger for ten. Thus twenty would be the first two fingers upraised (similar to the V for Victory sign but less spread, palm away from self) and then you cross them and turn it around to indicate ten. This is 2 then 10 which in Mandarin's counting system is 20.
Once you learn this, buying anything becomes much easier and you don't even have that problem with the Cantonese accent confusing 4 and 10.