How to set different page size in gird view

See more:

ASP

I want to set different page size in grid view.
i.e. in first page only 5 record second 25 and third page need record 100

What I have tried:

<asp:GridView ID="gridview" AllowPaging="true" PageSize="10" OnPageIndexChanging="gridview_PageIndexChanging" runat="server" /> 

protected void gridview_PageIndexChanging(object sender, GridViewPageEventArgs e){
    FillGrid();
    gridview.PageIndex = e.NewPageIndex;
    gridview.DataBind();
}