diff --git a/lib/quote.rb b/lib/quote.rb
index 6d35c56..d041567 100644
--- a/lib/quote.rb
+++ b/lib/quote.rb
@@ -60,13 +60,12 @@ class Quote
     rates
   end
 
+  # I'm mimicking the apparent convention of the ECB here.
   def round_rate(rate)
     if rate > 100
       rate.round(2)
-    elsif rate > 10
-      rate.round(3)
     else
-      rate.round(4)
+      Float("%.#{5}g" % rate)
     end
   end
 end
diff --git a/spec/quote_spec.rb b/spec/quote_spec.rb
index d0205f2..f400164 100644
--- a/spec/quote_spec.rb
+++ b/spec/quote_spec.rb
@@ -33,19 +33,25 @@ describe Quote do
     end
   end
 
-  describe 'when given a non-euro base' do
-    let(:quote) { Quote.new(base: 'USD') }
+  describe 'when given a custom base' do
+    let(:quote) { Quote.new(base: 'FOO') }
 
     it 'quotes rates against that currency' do
-      stub_rates 'USD' => 1.25 do |quote|
-        rate = quote.rates['EUR']
-        rate.must_equal 0.8
+      stub_rates 'FOO' => 2 do |quote|
+        quote.rates.keys.must_include 'EUR'
       end
     end
 
     it 'does not quote the base currency' do
-      stub_rates 'USD' => 1.25 do |quote|
-        quote.rates.keys.wont_include 'USD'
+      stub_rates 'FOO' => 2 do |quote|
+        quote.rates.keys.wont_include 'FOO'
+      end
+    end
+
+    it 'rounds to five significant digits' do
+      stub_rates 'FOO' => 0.6995 do |quote|
+        rate = quote.rates['EUR']
+        rate.must_equal 1.4296
       end
     end
   end