The minimum investment is 1% of the masternode.
If your send less then 1% to the address of the service the investment is returned back to your wallet.
New masternode share percent is always an integer value. Shares could be 1%, 2%, 3%, 45%, 74% but not 74.65%. This has been done to avoid extra small shares to fill the masternode up that could arise before. If you send 74.65% of the masternode, you get 74% masternode share and 0.65% is returned back to your wallet when the masternode is being started.
2Masternodes masternode shares and hosting: https://2masternodes.com/
2Miners mining pools: https://2miners.com/