diff --git a/odoo/addons/base/models/res_currency.py b/odoo/addons/base/models/res_currency.py
index e3624000a0e..c75ddfe0021 100644
--- a/odoo/addons/base/models/res_currency.py
+++ b/odoo/addons/base/models/res_currency.py
@@ -134,11 +134,7 @@ class Currency(models.Model):
            :param float amount: the amount to round
            :return: rounded float
         """
-        # TODO: Need to check why it calls round() from sale.py, _amount_all() with *No* ID after below commits,
-        # https://github.com/odoo/odoo/commit/36ee1ad813204dcb91e9f5f20d746dff6f080ac2
-        # https://github.com/odoo/odoo/commit/0b6058c585d7d9a57bd7581b8211f20fca3ec3f7
-        # Removing self.ensure_one() will make few test cases to break of modules event_sale, sale_mrp and stock_dropshipping.
-        #self.ensure_one()
+        self.ensure_one()
         return tools.float_round(amount, precision_rounding=self.rounding)
 
     @api.multi
@@ -162,6 +158,7 @@ class Currency(models.Model):
 
            With the new API, call it like: ``currency.compare_amounts(amount1, amount2)``.
         """
+        self.ensure_one()
         return tools.float_compare(amount1, amount2, precision_rounding=self.rounding)
 
     @api.multi
@@ -177,6 +174,7 @@ class Currency(models.Model):
 
            With the new API, call it like: ``currency.is_zero(amount)``.
         """
+        self.ensure_one()
         return tools.float_is_zero(amount, precision_rounding=self.rounding)
 
     @api.model
diff --git a/odoo/addons/base/tests/test_float.py b/odoo/addons/base/tests/test_float.py
index 4447b9de1c0..4dbf1f5f139 100644
--- a/odoo/addons/base/tests/test_float.py
+++ b/odoo/addons/base/tests/test_float.py
@@ -201,12 +201,30 @@ class TestFloatPrecision(TransactionCase):
         with self.assertRaises(AssertionError):
             float_is_zero(0.01, precision_digits=3, precision_rounding=0.01)
 
+        with self.assertRaises(AssertionError):
+            float_is_zero(0.0, precision_rounding=0.0)
+
+        with self.assertRaises(AssertionError):
+            float_is_zero(0.0, precision_rounding=-0.1)
+
         with self.assertRaises(AssertionError):
             float_compare(0.01, 0.02, precision_digits=3, precision_rounding=0.01)
 
+        with self.assertRaises(AssertionError):
+            float_compare(1.0, 1.0, precision_rounding=0.0)
+
+        with self.assertRaises(AssertionError):
+            float_compare(1.0, 1.0, precision_rounding=-0.1)
+
         with self.assertRaises(AssertionError):
             float_round(0.01, precision_digits=3, precision_rounding=0.01)
 
+        with self.assertRaises(AssertionError):
+            float_round(1.25, precision_rounding=0.0)
+
+        with self.assertRaises(AssertionError):
+            float_round(1.25, precision_rounding=-0.1)
+
     def test_amount_to_text_10(self):
         """ verify that amount_to_text works as expected """
         currency = self.env.ref('base.EUR')
diff --git a/odoo/tools/float_utils.py b/odoo/tools/float_utils.py
index 12881503f32..47b5d72c069 100644
--- a/odoo/tools/float_utils.py
+++ b/odoo/tools/float_utils.py
@@ -26,6 +26,8 @@ def _float_check_precision(precision_digits=None, precision_rounding=None):
     assert (precision_digits is not None or precision_rounding is not None) and \
         not (precision_digits and precision_rounding),\
          "exactly one of precision_digits and precision_rounding must be specified"
+    assert precision_rounding is None or precision_rounding > 0,\
+         "precision_rounding must be positive, got %s" % precision_rounding
     if precision_digits is not None:
         return 10 ** -precision_digits
     return precision_rounding
@@ -51,7 +53,8 @@ def float_round(value, precision_digits=None, precision_rounding=None, rounding_
     """
     rounding_factor = _float_check_precision(precision_digits=precision_digits,
                                              precision_rounding=precision_rounding)
-    if rounding_factor == 0 or value == 0: return 0.0
+    if rounding_factor == 0 or value == 0:
+        return 0.0
 
     # NORMALIZE - ROUND - DENORMALIZE
     # In order to easily support rounding to arbitrary 'steps' (e.g. coin values),