The pay-per-use US roaming buckets are based on a customer's billing cycle. If it is the last day of a customer's billing cycle and they sent 1 per per use text and then on the second day they sent a 2nd text that's $10 for 2 texts. This is in effect a roaming bundle and not really pay per use.
First, this needs to be clarified in the Koodo FAQ.
And second, change the pay per use rates to truly pay per use. To Per MB ($0.25/MB) and Per SMS ($0.05/sms)