At restraunts, I used to tip 10% - double GST, whatever that worked out too, and I thought that was fine. Started dating a (now former) server, and she said tipping is minimum 15-20%

Talked to another friend who's serving, and she said tipping is 10-15%. I now tip ~15%.
At bars, I top lower, $0.50 to $1.00. Never understood why I would need to tip more at a bar, how hard can it be to take the cap off and hand you a beer?