"What does "minimum $10 (or $20) purchase required" mean?
To use store coupons that include a minimum purchase requirement, you must spend a minimum dollar amount on that shopping trip. You will reach the minimum purchase amount based upon total purchases before your Club Card discount is applied. This total will include the coupon item's regular price, not the discounted price. For example, the regular retail price of a box of Cheerios (before coupon and before Club Card discounts) will count toward the minimum purchase required in order to use the Cheerios coupon.

If you are using several store coupons in a shopping trip, you will only need to meet one minimum purchase requirement. For example, if you are using three coupons, and they each specify a minimum purchase requirement of $20, your minimum purchase requirement for the total shopping trip is $20, and not $60."

This is copied/pasted directly from Safeway's website, here:
Safeway - Savings Tips