Toys"R"Us takes an extra 20% off clearance items via coupon code "CLEARANCE20". Shipping adds $5.99, but orders of $29 or more bag free shipping. (In-store pickup may also be available.) Some exclusions may apply.
After you're done saving on TRU's current deals, take a look at What to Expect From Toys"R"Us Black Friday Sales in 2017.
If you aren't using any of these three methods for significantly saving on laundry detergent, you are washing money down the drain.