According to the dictionary (and matching my own non-native pronunciation), cactus is /ˈkæktʌs/, practice is /ˈpɹæktɪs/
The terminal /tʌs/ is not quite the same thing as /tɪs/; since they are both unstressed, the difference can be hard to notice in fast speech, but becomes clear when enunciating.
The terminal /tʌs/ is not quite the same thing as /tɪs/; since they are both unstressed, the difference can be hard to notice in fast speech, but becomes clear when enunciating.