* htdocs/mantis/fetchBillingInformation.php: round quantities two digits after
  the decimal
Reverting "* sql/schema.sql: webfinance_invoice_rows.qtt now has 5 numbers after the   decimal instead of 2"
Revert "* sql/schema.sql: webfinance_invoice_rows.qtt now has 5 numbers after the"

This reverts commit 7264a7ad25fe766adfecc22c822f03ee9ca4bf8d.