In WinePulse the Wine Club Sign up conversion rate is the number of NON wine club tasters who joined the Wine Club.  For example if 30 of today's 50 tasters are non-wine club and 3 join the wine club, the wine club conversion rate is 3/30 i.e. 10%.  

Note in WinePulse the "Customer Type" field (Guest Customer, 1st Time Customer, Repeat Customer) is used to identify a non wine-club customer.  Individual tasting SKU's are not used for this calculation.

Currently the Tasting Room Wine Club Conversion includes Wine Club signups with "blank" Sales Associate.  These are generally website signups.