If you have a plan that does not qualify for Roam Like Home, you do not necessarily need to add a travel pack.
The pay-per-use rates are $1.45/min for airtime, 75¢ per sent text (the incoming ones are unlimited) and the data is $7.99/50 MB. The data is a day-pass, therefore, it is only valid for 24 hours even if you did not use the whole 50 MB.
Try to take into consideration what you will need your phone for, and save when using it outside of Canada by adding a Travel Pack beforehand.
For a one-time fee you'll enjoy a predetermined amount of minutes, data etc. and the overusage is discounted as well. All Travel Packs are valid for 31 days, including the date of purchase. However, you can use it all up in a few days depending on the lenght of your trip.
For example, for $40 (plus applicables taxes), you would get 50minutes of talktime, unlimited text messages and 200 MB for data transmissions. Check out www.rogers.com/travel for more info!