You can group rows in the grid by a particular column (field). Just add a GroupField to the GroupSettings.GroupFields collection.

There are numerous properties you can customize in each GroupField:
DataField - the column used for grouping
HeaderText - the text used for grouping. You can pass the value of the DataField using the {0} argument
GroupSortDirection - "Asc" or "Desc"
ShowGroupColumn - whether to show the grouping column in the grid or not

<%@ Page Language="C#" AutoEventWireup="true" CodeBehind="default.aspx.cs" Inherits="JQSuiteASPNETExample.examples.grouping.grandtotal._default" %>
<%@ Register Assembly="Trirand.Web" TagPrefix="trirand" Namespace="Trirand.Web.UI.WebControls" %>

<!DOCTYPE html>
<html lang="en-us">
<head id="Head1" runat="server">
    <meta charset="utf-8">
    <title>jqGrid for ASP.NET - grouping with grand total</title>
    <!-- The jQuery UI theme that will be used by the grid -->
    <link rel="stylesheet" type="text/css" media="screen" href="" />
    <!-- The jQuery UI theme extension jqGrid needs -->
    <link rel="stylesheet" type="text/css" media="screen" href="/themes/ui.jqgrid.css" />
    <!-- jQuery runtime minified -->
    <script src="/js/jquery-3.2.1.min.js" type="text/javascript"></script>
    <!-- The localization file we need, English in this case -->
    <script src="/js/trirand/i18n/grid.locale-en.js" type="text/javascript"></script>
    <!-- The jqGrid client-side javascript -->
    <script src="/js/trirand/jquery.jqGrid.min.js" type="text/javascript"></script>
     <style type="text/css">    
        body, html { font-size: 80%; }    
    <form id="form1" runat="server">    
    <trirand:JQGrid runat="server" ID="JQGrid1" DataSourceID="LinqDataSource1" 
        Width="600px" Height="100%" ondatarequested="JQGrid1_DataRequested">
            <trirand:JQGridColumn DataField="OrderID" PrimaryKey="true" Width="100" />
            <trirand:JQGridColumn DataField="OrderDate" />
            <trirand:JQGridColumn DataField="CustomerID"/>
            <trirand:JQGridColumn DataField="Freight" GroupSummaryType="Sum" GroupTemplate="Sum: {0}"/>
            <trirand:JQGridColumn DataField="ShipName" />
        <PagerSettings PageSize="12" />
        <GroupSettings CollapseGroups="false">
                    DataField="CustomerID" HeaderText="<b>{0}</b>" 
                    GroupSortDirection="Asc" ShowGroupColumn="true"/>
        <AppearanceSettings ShowFooter="true" />
    <asp:LinqDataSource ID="LinqDataSource1" runat="server" 
        AutoPage="true" AutoSort="true"
        Select="new (OrderID, OrderDate, CustomerID, Freight, ShipName)" 
    <br /><br />
    <trirand:codetabs runat="server" id="tabs"></trirand:codetabs>  

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Data;

namespace JQSuiteASPNETExample.examples.grouping.grandtotal
    public partial class _default : System.Web.UI.Page

        protected void JQGrid1_DataRequested(object sender, Trirand.Web.UI.WebControls.JQGridDataRequestedEventArgs e)
            DataTable dt = e.DataTable; // get only the current page data            
            decimal freightTotal = 0;             

            foreach (DataRow row in dt.Rows)
                decimal freightValue = (decimal)row["Freight"];                
                freightTotal += freightValue;

            JQGrid1.Columns.FromDataField("Freight").FooterValue = freightTotal.ToString();
            JQGrid1.Columns.FromDataField("CustomerID").FooterValue = "Total:";            
Switch theme:

Theming is based on the very popular jQuery ThemeRoller standard. This is the same theming mechanism used by jQuery UI and is now a de-facto standard for jQuery based components. The benefits of using ThemeRoller are huge. We can offer a big set of ready to use themes created by professional designers, including Windows-like themes (Redmond), Apple-like theme (Cupertino), etc. In addition to that any jQuery UI controls on the same page will pick the same theme.

Last, but not least, you can always roll your own ThemeRoller theme, using the superb Theme Editor

To use a theme, simply reference 2 Css files in your Html <head> section - the ThemeRoller theme you wish to use, and the jqGrid own ThemeRoller Css file. For example (Redmond theme):

<link rel="stylesheet" type="text/css" media="screen" href="/themes/redmond/jquery-ui-1.8.2.custom.css" />
<link rel="stylesheet" type="text/css" media="screen" href="/themes/ui.jqgrid.css" />