Guys I did this :
JQuery Code :
function gvDepositOrderDetail_OnRowChecked(checkBoxElement, newAmount, targetElement)
{
var amountElement = $find(targetElement);
var amount = amountElement.get_value() == ''? 0 : amountElement.get_value() - 0;
if (isNaN(amount)) {
amount = 0;
}
if (checkBoxElement.checked == false)
{
newAmount = newAmount * -1;
}
amount = amount + newAmount;
amountElement.set_value(amount) ;
}
from Code behind :
chk.Attributes.Add("onclick", string.Format("javascript:gvDepositOrderDetail_OnRowChecked(this,{0},'{1}');", lblAmount.Text, txtAmount.ClientID));