Hi, just wondered if anyone could help. I charge £6.50 p/h for babysitting and just say, for example, I sat for 4 hours = £26 - if they don't say anything after giving me £30, should I offer them the £4 difference or will it offend them? Don't want to appear presumptious! Thanks. P.S. I would always offer out of principal/good manners but wonder if it's taken (if they don't say anything) that they're happy to round up?!