Its good idea to give /27 because ripe ncc reserve /27 even if they give /29.

The reason RIPE reserves some space is to allow for growth and to be able to provide the LIR with a
The goal is not to allocate an LIR a /27 or /26 if they only need a /32. This contiguous block is also made so that the LIR can have a single BGP announcement for their IPv6 routes (which we, as router maintainers, would appreciate since it reduces the need for routers with larger FIB capacity).

Here is an random example from the RIPE Delegated file from ftp.ripe.net. You see that even a /25 is "reserved" if an allocation is done for a /29:

2001:3bc0::    29        allocated to LIR
2001:3bc8::    29        reserved
2001:3bd0::    28        reserved
2001:3be0::    27        reserved
2001:3c::      29        (This hole is missing in the RIPE delegated file, somebody knows why ?)
2001:3c08::    29        reserved
2001:3c10::    28        reserved
2001:3c20::    27        reserved