diff --git a/combo/apps/lingo/views.py b/combo/apps/lingo/views.py
index 52a73d53..67282f69 100644
--- a/combo/apps/lingo/views.py
+++ b/combo/apps/lingo/views.py
@@ -14,7 +14,7 @@
 # You should have received a copy of the GNU Affero General Public License
 # along with this program.  If not, see <http://www.gnu.org/licenses/>.
 
-from decimal import Decimal
+from decimal import Decimal, ROUND_HALF_UP
 import json
 
 from django.contrib.auth.models import User
@@ -55,13 +55,26 @@ class AddBasketItemApiView(View):
     def dispatch(self, *args, **kwargs):
         return super(AddBasketItemApiView, self).dispatch(*args, **kwargs)
 
+    def get_amount(self, amount):
+        if isinstance(amount, list):
+            d = sum([Decimal(a) for a in amount])
+        else:
+            d = Decimal(amount)
+        return d.quantize(Decimal('0.01'), ROUND_HALF_UP)
+
     def post(self, request, *args, **kwargs):
         # XXX: check request signature
 
         request_body = json.loads(self.request.body)
+        extra = request_body.get('extra', {})
 
-        item = BasketItem()
-        item.amount = sum([Decimal(x) for x in request.GET.getlist('amount')])
+        item = BasketItem(amount=0)
+
+        if request_body.get('amount'):
+            item.amount += self.get_amount(request_body['amount'])
+
+        if extra.get('amount'):
+            item.amount += self.get_amount(extra['amount'])
 
         try:
             if request.GET.get('NameId'):