CHANGELOG entry for 28442

CHANGELOG.md

@@ -7,6 +7,11 @@ and this project adheres to [Semantic Versioning](http://semver.org/spec/v2.0.0.
 
 ## [Unreleased]
 
+### Fixed
+
+- Make sbws round to 3 significant figures in torflow rounding mode, rather
+  than rounding to the nearest 1000 kilobytes (#28442).
+
 ## [1.0.2] - 2018-11-10
 
 ### Fixed