handgun

I am attempting to estimate the maintenance cost on a IP based digital surveillance system. The cost of the system is $1 million (includes cameras, infrastructure, servers, etc.). Are there percentages or acceptable ratios that can be utilized to calculate the maintenance cost for this system. In other words, is it acceptable to use a figure of 10% to calculate the maintenance costs on a $1 Mil system? I am thinking there must be an industry standard for calculating maintenance costs?