Double-add, yes, please DO NOT overtip. It would be dreadful if we become the tipping culture like in US. I noticed that in the UK, tipping is becoming very like in US, worrying.

It is very common here to just round up the bill. Only for exceptional service do we ever tip, but even that is never really up to 10%, I would say in the region of 5 %, of course IF it is based on total of bill.

To me tipping is a way of showing your gratitude for the exceptional service, but not when service is as is from the book. And of course it is absurd to be made compulsory like in the US.