in very official case, we say 七点二十八分 for example in news etc.
in ordinary cases, we say 快(almost)七点半了 or 差几分钟七点半 or 差两分七点半(two to seven)
we can also say 七点半 even it is 7:28
7:14------快七点十五了 or 快七点一刻了（一刻 means a quarter）
u must pay attention: u can just use this when it hasn't arrived 7:30. If it has surpassed 7:30, such as 7:31 7:32 etc, u must say 七点半多
for all of 了 here, it doesn't mean the pass, so 现在七点多 = 现在七点多了 了 here just highlights the fact that it has passed seven o'clock.