diff --git a/core/DataTable.php b/core/DataTable.php
index 656ff1c480648bf47f5bd89e34f954d94b247d41..56879136d20adf21de981801434836166e8c6448 100644
--- a/core/DataTable.php
+++ b/core/DataTable.php
@@ -449,7 +449,9 @@ class Piwik_DataTable
                 // if the row has the subtable already
                 // then we have to recursively sum the subtables
                 if (($idSubTable = $row->getIdSubDataTable()) !== null) {
-                    $rowFound->sumSubtable(Piwik_DataTable_Manager::getInstance()->getTable($idSubTable));
+                    $subTable = Piwik_DataTable_Manager::getInstance()->getTable($idSubTable);
+                    $subTable->setColumnAggregationOperations($this->columnAggregationOperations);
+                    $rowFound->sumSubtable($subTable);
                 }
             }
         }
diff --git a/core/DataTable/Row.php b/core/DataTable/Row.php
index 2a0550bd88c48f5f6bcd6a816d4de3557c8595f5..ff5b5de25bbaa996aa32b78f90780e91154b8491 100644
--- a/core/DataTable/Row.php
+++ b/core/DataTable/Row.php
@@ -282,6 +282,7 @@ class Piwik_DataTable_Row
             $thisSubTable = new Piwik_DataTable();
             $this->addSubtable($thisSubTable);
         }
+        $thisSubTable->setColumnAggregationOperations($subTable->getColumnAggregationOperations());
         $thisSubTable->addDataTable($subTable);
     }
 
diff --git a/core/Piwik.php b/core/Piwik.php
index 961f561a4e54b512056064acc3814542406bdb5b..2dd7ba9b0c5528d62ae7e72e086a39588c0ae7d8 100644
--- a/core/Piwik.php
+++ b/core/Piwik.php
@@ -1437,7 +1437,8 @@ class Piwik
         $minutes = floor($minusDaysAndHours / 60);
 
         $seconds = $minusDaysAndHours - $minutes * 60;
-		$seconds = round($seconds, 2);
+        $precision = ($seconds > 0 && $seconds < 0.01 ? 3 : 2);
+		$seconds = round($seconds, $precision);
 
         if ($years > 0) {
             $return = sprintf(Piwik_Translate('General_YearsDays'), $years, $days);
diff --git a/tests/PHPUnit/Core/PiwikTest.php b/tests/PHPUnit/Core/PiwikTest.php
index a4db97b17a6545d846360bb5338ab46ea1d62921..ade7e91778b225daad4d69c56d59ac47cb502201 100644
--- a/tests/PHPUnit/Core/PiwikTest.php
+++ b/tests/PHPUnit/Core/PiwikTest.php
@@ -91,6 +91,7 @@ class PiwikTest extends DatabaseTestCase
             array(1.342, array('1.34s', '00:00:01.34')),
             array(.342, array('0.34s', '00:00:00.34')),
 			array(.02, array('0.02s', '00:00:00.02')),
+            array(.002, array('0.002s', '00:00:00')),
 			array(1.002, array('1s', '00:00:01')),
 			array(1.02, array('1.02s', '00:00:01.02')),
 			array(1.2, array('1.2s', '00:00:01.20')),