I have /29 from ISP and I would like to do something like this,

My vlan 10 192.168.10.0 -> public IP .226
VLAN 20 192.168.20.0 -> public IP .227
VLAN 30 192.168.30.0 -> public IP .228

Is it possible and how?

My guess would be by having three masquerade rules.
Here is a topic that can be helpful:
viewtopic.php?t=142214