Set Left Locator by Rounded Playhead

Set the left locator to the nearest barline to the playhead. Rounding can cause the playhead to move earlier, or later in the timeline.

Use the cycle area in Logic Pro — Apple Support

Set Rounded Locators by Regions/Events/Marquee: Rounds the position of the locators to the barline that is nearest to the beginning and end points of the selected regions or events, or the marquee selection.