diff --git a/cookbook/resources/demo-database/dbt/models/staging/_schema.yml b/cookbook/resources/demo-database/dbt/models/staging/_schema.yml
index 5e285f1..aba4c78 100644
--- a/cookbook/resources/demo-database/dbt/models/staging/_schema.yml
+++ b/cookbook/resources/demo-database/dbt/models/staging/_schema.yml
@@ -27,6 +27,10 @@ models:
         data_tests:
           - accepted_values:
               values: ['completed', 'pending', 'cancelled', 'shipped', 'processing', 'return_pending']
+      - name: tax_amount
+        description: Estimated tax at 8% of order total
+      - name: gross_total
+        description: Order total + shipping + tax - discounts
 
   - name: stg_jaffle_shop__order_items
     description: Order line items with calculated line totals
@@ -39,12 +43,14 @@ models:
         description: Quantity * unit price
 
   - name: stg_stripe__payments
-    description: Payment transactions with risk scoring
+    description: Payment transactions with risk scoring (test transactions excluded)
     columns:
       - name: payment_id
         data_tests:
           - unique
           - not_null
+      - name: currency
+        description: Payment currency (defaults to USD)
       - name: payment_status
         data_tests:
           - accepted_values:
diff --git a/cookbook/resources/demo-database/dbt/models/staging/stg_jaffle_shop__orders.sql b/cookbook/resources/demo-database/dbt/models/staging/stg_jaffle_shop__orders.sql
index 08b44b9..f2208b7 100644
--- a/cookbook/resources/demo-database/dbt/models/staging/stg_jaffle_shop__orders.sql
+++ b/cookbook/resources/demo-database/dbt/models/staging/stg_jaffle_shop__orders.sql
@@ -11,6 +11,11 @@ cleaned as (
         coalesce(order_total, 0) as order_total,
         coalesce(shipping_cost, 0) as shipping_cost,
         coalesce(discount_amount, 0) as discount_amount,
+        round(coalesce(order_total, 0) * 0.08, 2) as tax_amount,
+        coalesce(order_total, 0)
+            + coalesce(shipping_cost, 0)
+            + round(coalesce(order_total, 0) * 0.08, 2)
+            - coalesce(discount_amount, 0) as gross_total,
         coupon_code,
         created_at,
         updated_at
diff --git a/cookbook/resources/demo-database/dbt/models/staging/stg_stripe__payments.sql b/cookbook/resources/demo-database/dbt/models/staging/stg_stripe__payments.sql
index 71626b8..392ddbd 100644
--- a/cookbook/resources/demo-database/dbt/models/staging/stg_stripe__payments.sql
+++ b/cookbook/resources/demo-database/dbt/models/staging/stg_stripe__payments.sql
@@ -8,6 +8,7 @@ cleaned as (
         order_id,
         payment_method,
         amount as payment_amount,
+        'USD' as currency,
         status as payment_status,
         created_at as payment_created_at,
         card_last_four,
@@ -18,6 +19,7 @@ cleaned as (
     from source
     where id is not null
       and amount > 0
+      and billing_email not like '%@test.com'
 )
 
 select * from cleaned