Here is a simple back of the envelope calculation to demonstrate the idea.

  Revenue Cost Gross Rate Tax Profit
     1000  700  300    20  60    240
     1020  700  320    25  80    240
     1000  680  320    25  80    240

Of course, in reality there are many more factors to keep in mind e.g. you can't increase the price while expecting the sales to stay steady, and you can't expect the quality to maintain (and hence keeping the sales) while reducing the cost (personnel or material). But the idea is that the directors can find many ways to keep the shareholders happy even in the face of corporate tax hike.