but 10:15 seems to be creeping in.
That's the form used in the US (which doesn't normally use the 24 hour clock). I have no idea about the UK. I'm used to the Polish version now, but it took some time.
For me, $15 looks.... like it's missing something. I think $15.00 looks much better (no reason Poles should).
Also Poles tend to reverse the use of commas and periods in large numbers (or use a space instead of a comma) so that 15,345.37 becomes 15 345,37