You can add a pattern restriction:
<xsd:simpleType name="fractionalSalary">
<xsd:restriction base="xsd:decimal">
<xsd:fractionDigits value="2" />
<xsd:minExclusive value="0" />
<xsd:pattern value="\d+\.\d{2}" />
</xsd:restriction>
</xsd:simpleType>
This means that the decimal supplied must match the regex.
At this point, you can probably get rid of the fractionDigits element too, as that constraint is covered by the regex.