question about using tokuDB or InnoDB for financial data
A few things to note:


XtraDB Cluster doesn't scale writes (horizontally), i.e. you can't increase number of writes by adding more nodes. However, 350,000 records per day is approx. 4 record per second, which is no problem at all for XtraDB Cluster (or any other replication topology), at least as long as the nodes are on the same network. 
XtraDB Cluster only supports the XtraDB / InnoDB table storage engine, so TokuDB isn't an option if you want to use that particular cluster technology. 
4 nodes isn't a good number. You should be using an odd number (3, 5, ...) of nodes, or an even number of nodes + one node with garbd, the Galera arbitrator.


XtraDB (which is InnoDB with a few patches from Percona) is a tried and tested technology, and XtraDB / InnoDB is the default storage engine in MySQL, Percona and MariaDB. InnoDB is being developed and supported by MySQL (owned by Oracle). 

TokuDB is newer, it doesn't have as many years of usage and development. If I understand correctly, TokuDB is developed by Tokutek, now owned by Percona.

With these considerations, in a choice between these two technologies for a system for financial transaction data, I would probably go with XtraDB.