If you just started getting into the habit of putting money into a savings account, the thought of investing that cash can feel intimidating. But investing a tiny bit is often better than not investing at all, even if you only have literal pennies to spare. That's the idea behind Acorns, an investment app that invests your spare change automatically without you having to think about it, according to NerdWallet.

To use it, you link your debit or credit cards to your Acorns account. The app then keeps track of every purchase you make, and with your permission, it rounds up those transactions to the nearest dollar, transferring that spare change to an Acorns investment portfolio.

These individual investments are almost too small to notice, and that's the point. Instead of investing an intimidating portion of your savings all at once, you invest small amounts that add up over time—hopefully making your money back and then some, with little risk or effort on your part. Acorns also gives you the option to choose how risky you want to be with your investments, with levels ranging from conservative to aggressive.

If you ever decide you're ready to start investing more than a few cents at a time, Acorns allows you to transfer larger amounts of money into your investment account, too, as long as it's more than $5. And if you ever feel like you're letting go of too much, you can shut off the automatic feature and choose which transactions to round up and invest manually.

To sign up for the service, you have to be willing to put down a little more than pocket change. Investing in one of its pre-built portfolios requires a minimum balance of $5. On top of that, you need to pay $1 a month for a taxable investment account, $2 a month for an IRA account, or $3 a month for both types of investment accounts and an Acorns checking account. (College students with a functioning .edu email address are eligible to try the taxable investment service free for four years.)

Now that your investments are taken care of, check out these other apps that can make being an adult less stressful.

[h/t NerdWallet]