[Limitation] SQL Server does not support variable precision decimals. The xs:decimal type represents arbitrary precision decimal numbers. Minimally conforming XML processors must support decimal numbers with a minimum of totalDigits=18. SQL Server supports totalDigits=38, but limits the fractional digits to 10. All xs:decimal instanced values are represented internally by the server by using the SQL type numeric (38, 10). [Item] 
Variable precision decimals