It's an idiotic code that some posters still use when discussing prices. $.5 means $150.00, $.6 means $160.00, $$.4 means $240.00, etc. It's stupid, and some posters fuck it up. Some others use colour codes, i.e. green = $20.00, red = $50.00, brown = $100.00, etc. It's just as idiotic and only slightly less confusing.
This practice is likely derived from a similar practice in the USA, where they use the names of men who are on the various denominations of bills, i.e., Franklins, Jacksons, etc. Unlike in Canada, prostitution is totally illegal in the USA, and some posters of reviews think LE is so dumb they won't understand the system.
This is Canada! Just state the amount you paid and be done with it!!