Hi Shree,
There is cut-throat competition going on in quoting, especially in manpower supply, facilities, security contract etc. Many tend to quote 0.1% or even '0'%. Some employer doesn't agree to such freak rates. But if everything is rightly evaluated 10 to 15% as service charge to the Contractor should be alright. But quoting is different and winning the tender is different as it's depend on the quotes of your competitors. Employers cannot justify picking higher %age of quote when there are lower rates quoted by others, unless such lower quotes are blacklisted.