As a Google Analytics user you are probably quite attached to the default reports in the user interface of Universal Analytics. It can be hard to make sense of the data in the BigQuery export tables.
Let me enable you to replicate the reports you're familiar with. I'll try to keep it basic here.
Sales performance report
In the Conversions | (Enhanced) Ecommerce | Sales performance report you'll find data about the performance of your enhanced ecommerce activities, segmented by
transaction id and
select hits.item.transactionid, -- date, ifnull(sum(hits.transaction.transactionrevenue)/1000000,0) as revenue, ifnull(sum(hits.transaction.transactiontax)/1000000,0) as tax, ifnull(sum(hits.transaction.transactionshipping)/1000000,0) as shipping, ifnull(sum(hits.refund.refundAmount),0) as refund_amount, ifnull(sum(case when hits.ecommerceaction.action_type = '6' then productquantity else null end),0) as quantity from `bigquery-public-data.google_analytics_sample.ga_sessions_20160801`, unnest(hits) as hits, unnest(product) as product where totals.visits = 1 and hits.item.transactionid is not null group by transactionid -- ,date order by revenue desc