Long story short? You'll get more back if you save up coins for the higher tiers and you'll get more coins when you buy coffees and supplies that have point multipliers during promotions!
The long version: as far as earning coins, our baseline is 3 coins for every dollar you spend (3%). From time to time, we'll offer promotions on certain items and coffees where you can earn as much as double coins (6 coins for every dollar spent)!
When it comes to getting the most bang for your coins, we currently offer 3 redemption tiers. At the lowest (500 coins), you'll get $5 off. That equates to a straight 3% value (if you got the 3 points to a dollar baseline). At 1000 coins you get $12 off which is 3.6% and at 2000 coins you get $26 off for 4%!