silly tip test

ch00.asciidoc

@@ -32,6 +32,11 @@ Or Bob might say _"That's one-dollar-fifty, or fifteen milibits"_.
 
 Alice would use a smartphone to scan the barcode on display and send the payment. Her smartphone would show a payment of +0.0150 BTC+ to +Bob's Cafe+ and she would select +Send+ to authorize the payment. Within a few seconds (about the same time as a credit card authorization), Bob would see the transaction on the register, completing the transaction. Alice has purchased a cup of coffee for 15 millibits (or 0.015 bitcoin)
 
+[TIP]
+====
+In the USA, it is customary to tip 20% for good service at coffee shops. Alice may choose to tip in dollars, or may add bitcoin. 
+====
+
 ==== A currency
 
 Bitcoin is a currency, the operates much like any "foreign" currency. The main difference is that it is not issued by a national government. Bitcoin currency units are called "bitcoins". Unlike traditional currencies, bitcoins are divisible to much smaller units. The smallest unit is the _satoshi_, one hundred-millionth of a bitcoin (1/100,000,000). Bitcoin can be exchanged for other currencies at specialized currency exchanges that support crypto-currencies like bitcoin. There, a customer can exchange US dollars ($) or Euros (E) for bitcoin, at the prevailing market exchange rate.