Input model changes from Integer to String when changed

Have a kind of price range/rating functionality based on an inputs model. On load, when it's set from the backend, it starts off as an integer, but when you type in it, it changes to a string. Is there any way in Angular to declare the value of an input as integer?

HTML:

<input type="text" name="sellPrice" id="sellPrice" class="sell-price" data-ng-model="menu.totalPrice" data-ng-change="updateMenuPriceRange()"required>

JS:

$scope.updateAggregatePricing();

if ($scope.menu.totalPrice === 0) {
    $scope.menuPriceRange = "";
} else if ($scope.menu.totalPrice < 10) {
    $scope.menuPriceRange = "$";
} else if ($scope.menu.totalPrice >= 10 && $scope.menu.totalPrice <= 12.50) {
    $scope.menuPriceRange = "$$";
} else if ($scope.menu.totalPrice >= 12.51 && $scope.menu.totalPrice < 15) {
    $scope.menuPriceRange = "$$$";
} if ($scope.menu.totalPrice >= 15) {
    $scope.menuPriceRange = "$$$$";
} else {
    $scope.menuPriceRange = "";
}