"It's two o'clock sharp."
Both 现在两点整 and 现在两点钟 are grammatically correct. But the former one put more emphasis on the exactness of the time.
For some reason Chinese always wants 现在 when mentioning the current time. 现在 Isn't used to emphasise the time, Right Now! Like we would use it in English. It's just necessary. And if you omit 现在 you'll actually be misunderstood a lot. I've lived in china for 4.5 years.
现在 indicates that this is the current time, as “it's" indicates that this is the current time in English.
In the Chinese to English, I wrote "It's two o'clock sharp," for exactly this Chinese sentence, but it was not accepted because I left out "now." I think my answer should have been accepted.
I'm a native and I've never heard people say 两点钟整 although that's grammatical. It is always 两点整.