Payment of increments depends on the profitability of the respective organization and market situations facing the company. If you expect a good market, you can pay good increments so that you can make your employees happy and retain them. Normally, an increment of ten to fifteen percent will be the industry standard. But at the same time, you can also consider an increase at par with the increase in the cost of living index only for those whose performance has been rated as very poor. If you have the practice of paying Dearness Allowance, that would justify an increment to such employees. However, most IT companies do not pay DA but have a salary structure with a minimum amount as Basic (reason not known...!) and higher amounts on other allowances. The increment should be reflected in the basic pay component as well; otherwise, the same will lead to other legal complications in the future. The percentage of increase shall be on the gross salary, and the amount arrived at shall be equitably distributed among the various components of salary.
With regard to bonus payment, you should work out a plan in which you have to define who all will be entitled to get a bonus and how much the rate of the bonus shall be. Statutory bonus is governed by the Payment of Bonus Act, and if you follow the same, then people with a salary of more than Rs 21,000 will not come under the bonus brackets, but only a few will be available as employees entitled to get a bonus. If your remuneration structure itself is designed with a component called a bonus, then that shall be paid irrespective of your profitability. Depending upon the profitability of the organization, the rate of the bonus shall vary from 8.33% to 20%.