1) places that add the tip onto the bill automatically. The type of place that does this usually has the kind of staff who've done the least to earn the tip.
2) places that include the tips in the staff salary, so they pay them a base of less than minimum wage.
I usually top up the bill to a round amount, so a £36 bill will be rounded up to £40 (11%). If service has been very good I'll leave the tip as cash on the table, so the table staff get to pocket it directly...
I never tip as I expect the cost of a meal to include an amount for wages. I don't expect to tip the cashier at Waitrose when she swipes my groceries and as good service should be the norm I am not inclined to tip when I receive it.
I accidentally gave a $40 tip to a Mexican in the middle of the night in Houston thinking I gave 2 $1 bills for showing me where a taxi was. All $ bills are the same colour and size. It did seem to make his day however. In mitigation I had been traveling for 3 days & it was dark.