You could try using multiple div with fixed width and eval keyword to achieve your scenario. Here is the snippet the I come up during my test for this scenario:

<ISWebGrid:WebGridColumn Name="View_WebGridColumn" EditType="NoEdit"
    ColumnType="Template" Caption="Custom View" Width="200px">
    <CellTemplate>
        <div style="width:148px; float:left; line-height: 20px; height: 20px; overflow:hidden; border-right: solid 1px #add1ff; padding-left:2px;"><%# Eval("ProductName") %></div>
        <div style="width:48px; float:left; line-height: 20px; height:20px; padding-left:2px;"><%# Eval("UnitPrice") %></div>
    </CellTemplate>
    <CellStyle>
        <Padding Bottom="0px" Left="0px" Right="0px" Top="0px" />
    </CellStyle>
</ISWebGrid:WebGridColumn>

Set the div width so it will fill all the column width. We must also set the div height to match the column height and finally set the cell padding to 0.