Code:
<value condition="String.StartsWith(ListItem.Duration,01:00:)">1h00</value>
<value condition="String.StartsWith(ListItem.Duration,01:01:)">1h01</value>
<value condition="String.StartsWith(ListItem.Duration,01:02:)">1h02</value>
<value condition="String.StartsWith(ListItem.Duration,01:03:)">1h03</value>
<value condition="String.StartsWith(ListItem.Duration,01:04:)">1h04</value>
<value condition="String.StartsWith(ListItem.Duration,01:05:)">1h05</value>
<value condition="String.StartsWith(ListItem.Duration,01:06:)">1h06</value>
<value condition="String.StartsWith(ListItem.Duration,01:07:)">1h07</value>
<value condition="String.StartsWith(ListItem.Duration,01:08:)">1h08</value>
<value condition="String.StartsWith(ListItem.Duration,01:09:)">1h09</value>
<value condition="String.StartsWith(ListItem.Duration,01:10:)">1h10</value>
<value condition="String.StartsWith(ListItem.Duration,01:11:)">1h11</value>
<value condition="String.StartsWith(ListItem.Duration,01:12:)">1h12</value>
<value condition="String.StartsWith(ListItem.Duration,01:13:)">1h13</value>
<value condition="String.StartsWith(ListItem.Duration,01:14:)">1h14</value>
... etc ...
<value condition="String.StartsWith(ListItem.Duration,05:49:)">5h49</value>
<value condition="String.StartsWith(ListItem.Duration,05:50:)">5h50</value>
<value condition="String.StartsWith(ListItem.Duration,05:51:)">5h51</value>
<value condition="String.StartsWith(ListItem.Duration,05:52:)">5h52</value>
<value condition="String.StartsWith(ListItem.Duration,05:53:)">5h53</value>
<value condition="String.StartsWith(ListItem.Duration,05:54:)">5h54</value>
<value condition="String.StartsWith(ListItem.Duration,05:55:)">5h55</value>
<value condition="String.StartsWith(ListItem.Duration,05:56:)">5h56</value>
<value condition="String.StartsWith(ListItem.Duration,05:57:)">5h57</value>
<value condition="String.StartsWith(ListItem.Duration,05:58:)">5h58</value>
<value condition="String.StartsWith(ListItem.Duration,05:59:)">5h59</value>