At first glance, some of the rewards can seem paltry. For instance, the Chase Freedom card offers 3% cash back on purchases that fall into one of 15 categories and 1% cash back on everything else. Many offers on FatWallet provide low single digit savings. Not exactly mind-blowing amounts. So is it worth it?

Is it worth signing up for and keeping track of these accounts for what amounts to a few percentage points off of your expenses?

I’m going to argue that the answer is a resounding yes for most people. And it all has to do with the low amount of their income that most people save.

These days, according to the US Department of Commerce, Americans on average save about 4% of their after-tax income. The other 96% goes out the door toward goods and services – rent, food, clothing, that new gadget you were just dying to have. The low savings rate means that even small discounts on your expenses can make a big difference in the amount you can save. Take a look at the table below.

On the left, you can see a typical month’s worth of savings for someone who socks away 4% of their after-tax income. $3,000 comes in, $2,880 goes toward expenses, and the rest is saved – $120.

On the other hand, imagine using discounts, coupons, or rewards programs that save you 4% every month on all your expenses. Those discounts nearly double the amount you can save, bringing it up to $235! The 4% in discounts is effectively added to your savings rate, making it nearly 8% instead of 4%!

Rewards or discount amounts should not be looked at on their own. They seem small by themselves. Rather, they should be compared to the percentage of your income that you are able to save.

The less you are saving, the more willing you should be to use discounts or rewards programs. For someone who saves a lot of their income, the 4% in rewards won’t make nearly as much of a difference. But for someone who saves little to no percentage of their income, getting a small percentage of expenses back via coupons, discounts, or rewards can make the difference between saving little to nothing and saving multiples more.

The key is to think about your discounts in relation to the percentage of income you can put away.

Here’s how it works. You sign up for an account at rewardsnetwork.com, and place a credit card on record. Every time you eat at a restaurant that’s part of the network, you’ll get a certain percentage of your bill back as cash. That’s it. There is no coupon clipping or codes to remember. Rewards Network tracks credit card usage at each of its participating restaurants, and when it sees your card used, it credits your card with the reported amount of cash back.

You can search for participating restaurants on the Rewards Network website and see how much cash back each place is offering. The majority of eateries in my neighborhood are offering 10% back, but there are others offering 20% and even 40%! The list of restaurants on the site also comes complete with a description of each place and reviews by users, so you can decide on a great place to eat in addition to one that will also pay you a little cash.

Savvy savers will also realize that you can double or even triple up on the savings by using Rewards Network in combination with restaurant coupons (from Entertainment for instance) and after reserving a table at a place like OpenTable.

Very savvy savers will realize that you can even use these discounts to get a free meal or more if you dine in groups. If you and four friends went to a bar with a 20% Rewards Network discount and each of your friends paid cash for their share of the bill, you could put the entire bill on your credit card and collect the cash from them. You’d effectively be paying your 20% of the bill, but you’d get that money back! Some might find this deceitful, so another approach is to simply share the wealth and tell your friends that everyone gets 20% off. Not bad.

Rewards Network has mobile device applications too, so you can search for cash back restaurants on-the-go, on your iPhone or Blackberry. You can also register up to five credit or debit cards on your account, and the percentage of money that you get back includes tax and your tip!

Bottom line: If you dine out (ever), the Rewards Network program is the best around for receiving valuable cash back discounts. And it’s effortless to do so.