Dear Ragesh,
There is no specific guideline regarding the percentage of salary to Sales/Turnover. In my opinion, the percentage depends on the nature of the industry, the market share enjoyed by the company (monopoly, competitive, or niche, etc.), the industry capacity, and the willingness of the top management to pay, etc.
The current trend in the industry is that employees are paid using two different pay structures - Fixed and Variable pay. While the fixed pay is the assured income for the employee, the variable pay is based on the performance of the individual and the company.
Regards, M.V. KANNAN