Please find sample XML code for displaying various options in 'Product Details' page for customizing the product with 'Percentage Based Pricing'. i.e. as the user selecting required options, the product price will be changed in runtime by fixed percentage on Web Price that is defined for respective options. 

<?xml version="1.0" encoding="UTF-8"?>
<FORM>
 <PAGES>
    <PAGE title="" id="var" type="HTML">
       <FIELDS>
          <FIELD type="TextBox" label="Person-in-charge (Name):" required="true">
             <PROPERTIES>
                <PROPERTY name="ID">Person</PROPERTY>
                <PROPERTY name="Width">250</PROPERTY>
                <PROPERTY name="cssClass">maintxt</PROPERTY>
             </PROPERTIES>
          </FIELD>
          <FIELD type="RadioButtonList" label="Select Shipping Method" required="true">
             <PROPERTIES>
                <PROPERTY name="ID">rdbRating1</PROPERTY>
                <PROPERTY name="RepeatColumns">3</PROPERTY>
                <PROPERTY name="RepeatDirection">Vertical</PROPERTY>
                <PROPERTY name="RepeatLayout">Table</PROPERTY>
                <PROPERTY name="TextAlign">Right</PROPERTY>
             </PROPERTIES>
             <LISTITEMS>
                <LISTITEM value="Normal">Normal</LISTITEM>
                <LISTITEM Percentage="10" value="Express">Express</LISTITEM>
                <LISTITEM Percentage="20" value="Extreme fast">Extreme fast</LISTITEM>
             </LISTITEMS>
          </FIELD>
          <FIELD type="CheckBoxList" label="How would you rate the quality of our products? ">
             <PROPERTIES>
                <PROPERTY name="ID">CHK3</PROPERTY>
                <PROPERTY name="RepeatColumns">3</PROPERTY>
                <PROPERTY name="RepeatDirection">Vertical</PROPERTY>
                <PROPERTY name="RepeatLayout">Table</PROPERTY>
                <PROPERTY name="TextAlign">Right</PROPERTY>
             </PROPERTIES>
             <LISTITEMS>
                <LISTITEM value="Poor">Poor</LISTITEM>
                <LISTITEM Percentage="5" value="Satisfactory">Satisfactory</LISTITEM>
                <LISTITEM Percentage="5" value="Good">Good</LISTITEM>
                <LISTITEM Percentage="5" value="Very good">Very Good</LISTITEM>
                <LISTITEM Percentage="5" value="Excellent">Excellent</LISTITEM>
             </LISTITEMS>
          </FIELD>
          <FIELD type="ImagePicker" label="Back Details :" required="true">
             <LISTITEMS>
                <LISTITEM>
                   <name>centre_folds</name>
                   <src>http://martjackstorage.blob.core.windows.net/in-resources/a9088bbb-df3e-47c4-839b-75a348f58f8c/Images/userimages/swatches/shirts/Back_Details/centre_folds.jpg</src>
                   <width>100</width>
                   <height>100</height>
                   <Percentage>10</Percentage>
         <price></price>
                </LISTITEM>
                <LISTITEM>
                   <name>nopleat</name>
                   <src>http://martjackstorage.blob.core.windows.net/in-resources/a9088bbb-df3e-47c4-839b-75a348f58f8c/Images/userimages/swatches/shirts/Back_Details/nopleat.jpg</src>
                   <width>76</width>
                   <height>87</height>
                   <Percentage>11</Percentage>
         <price></price>
                </LISTITEM>
                <LISTITEM>
                   <name>side_folds</name>
                   <src>http://martjackstorage.blob.core.windows.net/in-resources/a9088bbb-df3e-47c4-839b-75a348f58f8c/Images/userimages/swatches/shirts/Back_Details/side_folds.jpg</src>
                   <width>76</width>
                   <height>87</height>
                   <Percentage>12</Percentage>
         <price></price>
                </LISTITEM>
             </LISTITEMS>
          </FIELD>
    <FIELD type="DropDownList" label="Department:"><PROPERTIES><PROPERTY name="ID">Department</PROPERTY><PROPERTY name="Width">256</PROPERTY></PROPERTIES><LISTITEMS><LISTITEM  value="Information Technology">Information Technology</LISTITEM><LISTITEM Percentage="15" value="Finance and Accounts">Finance and Accounts</LISTITEM><LISTITEM Percentage="30" value="Yarn Marketing">Yarn Marketing</LISTITEM><LISTITEM Percentage="35" value="Fabric Marketing">Fabric Marketing</LISTITEM></LISTITEMS></FIELD>
       </FIELDS>
    </PAGE>
 </PAGES>
</FORM>


Note: The 'Percentage Based Pricing' is specified as mentioned below in the above XML Code: 

  <LISTITEMS>
  <LISTITEM value="Normal">Normal</LISTITEM>
  <LISTITEM Percentage="10" value="Express">Express</LISTITEM>
  <LISTITEM Percentage="20" value="Extreme fast">Extreme fast</LISTITEM>
  </LISTITEMS>