Many companies set their own minimum wages higher than the national rate, according to the Labour Market Trends survey by the Office for National Statistics (ONS).
Employers tend to pay at least £5.50 or £6 an hour rather than the national minimum wage (NMW) of £5.05 per hour for workers over the age of 22, the research revealed.
The higher rates indicate that companies would rather set their own rates of pay at round numbers and absorb the extra labour costs, ONS said.
The NMW is due to rise to £5.35 an hour (for employees over the age of 22) in October of this year and to £4.45 an hour (up from £4.25) for 18-21 year olds.
The NMW was introduced in 1999.