If you are finding that Smartlist and Navigation Lists export currency values with 5 decimals in Excel using Microsoft GP 2013, this was by design. Microsoft reworked the exports to make them faster and this is one of the side effects.
Smartlist and Navigation Lists export currency values with 5 decimals in Excel using Microsoft Dynamics GP 2013 – Dynamics GP Support and Services Blog – Microsoft Dynamics GP – Microsoft Dynamics Community
Microsoft & the GP EcosystemReporting & BIExcel & OfficeGP 2013
Archived post from 2013. Dynamics GP and the links it points to have changed since; check current documentation before relying on version-specific steps.