ng-click for checkbox angularjs

I am creating a web app in which i am getting expense information in my table now if there are 10 data

1)100

2)200

3)300

4)200

5)300

6)400

7)500

8)600

9)900

10)200

all these data will be shown to the user with each data having a checkbox like

<td></td>
<td><input type="checkbox" ng-click="updatefunction(a)" />

and my checkbox is calling a controller of angularjs

$scope.updatefunction = function (param) {
            $scope.updateparam = param;
            console.log($scope.updateparam.salary);
            $scope.totalsalary = Number($scope.totalsalary) + Number($scope.updateparam.salary);
            console.log($scope.totalsalary);
        }

on ng-click this controller will be called but if a user click twice the value is incrementing two times and if i used ng-checked (1 to 10) all the entries are being incremented, what i need to do, i want to increment but if a user unchecked or click multiple times(the value should be decrease),