As Peter N-H quite rightly states, there's no tipping in China other in in situations where foreigners have been stupid enough to introduce it, where is come in the form of stupid foreigner tax.

I've been out to hundreds of dinners here. The process when the bill comes at the end is for a discount to be negotiated rather than for a tip to be added.

Why?

It's the local culture. The Chinese are great traders and love to bargain.

To a restaurant manager the concept that someone might want to pay RMB900 when the bill is RMB820 is simply alien. Same with a shopleeper and a hotelier. So let's not introduce it, eh!

And, as already noted, the OP is not proposing tipping, but bribery and the corruption that's associated with it.