Go to the following link, sign up here [philips.com]
for 10$ off coupon, using 4 different email id's (You can play with dots for Gmail ID).
for 15% off coupon.
Wait for a while (may be a day, the coupons has 2-3 months expiry dates), you will receive two coupons one for 15% off, one for 10$ off.
You can apply at max 4 coupons per order, they stack up (10$ off coupons didn't stack up not sure why, but the 15% off coupon does). Extra offers also gets added like $10 extra off for some products.
Offer Valid till they fix this bug