How labour cost is worked out: hours × the pay rate in force on the day they were worked × (1 + burden). A raise in June doesn't re-cost the hours worked in March. Running timers count up to now.
A job's labour cost isn't just the wage. Burden is what you pay on top of every hour: CPP/QPP and EI premiums, vacation pay, WSIB/WCB premiums for the trade's rate class, Employer Health Tax, and any benefits. In the US it's FICA (Social Security and Medicare), FUTA/SUTA, workers' comp and benefits.
Take the percentages from your payroll provider and your WSIB/WCB rate notice. Estiquik doesn't guess them; it does the arithmetic:
Burdened rate = wage × (1 + burden %)
Rates are dated. When someone gets a raise, add a new rate from that date rather than changing the old one, so hours already worked keep the cost they had.