Centering Inline-Block Elements in CSS

For example, let's center inline-block elements:

<div class="parent">
	<span class="child">text</span>
	<span class="child">text</span>
	<span class="child">text</span>
</div>

.parent {
	text-align: center;
	padding: 10px 0;
	border: 1px solid red;
}
.child {
	display: inline-block;
	padding: 10px 20px;
	border: 1px solid green;
}

Given divs inside some parent:

<div class="parent">
	<div class="child">text 1</div>
	<div class="child">text 2</div>
	<div class="child">text 3</div>
</div>

.parent {
	padding: 10px 0;
	border: 1px solid red;
}
.child {
	padding: 10px;
	border: 1px solid green;
}

Convert the child divs to inline-block elements, give them a horizontal margin of 5px, and then center them horizontally relative to their parent.