You can show the Invoice rate of a placement in a e-mail template with the following code:
<cx:let name="finance" value="$activity.toJob" invoke="financeForTag:">
<cx:parameter name="0" value="invoiceRateTag"/>
<cx:write value="$finance.amount" numberFormat="#0.00"/>
<cx:write value="$finance.toUnitNode.value"/>
</cx:let>
For the purchase rate use:
<cx:let name="finance" value="$activity.toJob" invoke="financeForTag:">
<cx:parameter name="0" value="wageRateTag"/>
<cx:write value="$finance.amount" numberFormat="#0.00"/>
<cx:write value="$finance.toUnitNode.value"/>
</cx:let>