Well yeah, in the powers-that-be's view, that 5% mark is where most are working to keep spending money and fueling the economy, but enough people are unemployed that keeps wages within employers' control as they have a pool of labor to draw on to replace uppity employees.
According to this, the total number of people in the US labor force was 168,130,000 people, and 5% of that is 8,406,500 (remember that the workforce number includes people who are working or actively seeking work; it does not include those who are too young, have retired, or have given up looking for work). That's almost 8.5 million people looking for work, and to the fed and economists, that's an acceptable number of people struggling to keep the economy stable.