Ganjapreneur reports

Previously, tipping budtenders wasn’t permitted because it had surfaced that certain locations were modifying product prices based on whether or not and how much a customer tipped, essentially sidestepping the state-mandated excise tax. However, due to a dramatic restructuring of the state’s cannabis taxation process in 2015, parts of these concerns were negated.

http://www.ganjapreneur.com/washington-regulators-legalize-tips-for-budtenders/

Here’s the  WSLCB notice  issued  yesterday:

Effective immediately, customer tipping is now an allowable practice in licensed retail marijuana stores. However, tipping cannot be required or a condition of sale, nor can it be linked to the price of the product to avoid tax obligations. If a licensee allows tipping for their staff, licensees are reminded that there may be business or employee taxes associated with tips received.

WSLCB Marijuana Information Page
http://www.liq.wa.gov/marj/marijuana-2016