The 5%ers trading activities are all executed through their brokers, via the STP Market Execution. They have incorporated an ECN-Broker-Fees-Structure into their platform. The spread and commission are shown separately – the commission is $4 per lot round trip, which is 0.4 pips.
The spread for EUR/USD is about 0.1 to 0.5 pips.
The spread is variable, not fixed. During the night hours, when the volatility is relatively low, the spreads can get wide, especially during the rollover time (New-York midnight).