You see the amount in full before purchase. There is not really a published table of prices including taxes/fees/charges for revenue tickets either. Base fares are published, but the total price is not shown until purchase.
Although, there is a table for maximum redemption costs here:
http://www.britishairways.com/travel...z/public/en_us
Slightly O/T, but that page suggests very pricey zone 3 redemptions
$525,207 seems rather a lot, doesn't it?