Because all-inclusive doesn’t mean you don’t have to tip.

There is something about living in a country where the government has mandated a living wage that makes Aussies a bit skittish when it comes to tipping. It’s not that we don’t or won’t, it’s that sometimes we need a reminder, so here it is. If you’re on a cruise out of Australia, be sure to tip your room stewards at the very least. Suffice to say, maritime hourly wages aren’t as high as Aussie shore-based ones and many of the people tidying up after you send most of what they earn back home to support their families.

How much do you tip on a cruise?
Travel guide Frommers has most cruise lines suggesting a tip of US$10-$12 per passenger per day. That’s for everything. Extending that then, a week’s cruise should be budgeted at around 100 per person when you factor in the conversion from US to A$.

How to tip on a cruise boat?
It’s simple, just hand whoever is serving you some cash. If you're on a cruise out of the US for example, you'll see cash changing hands constantly. Leave some in your cabin with a note thanking the steward. This is important so they know it’s for them. Alternatively, if that’s all a bit of hassle when working with a cruise card or feels awkward, you can always hit up the reception desk to add tips to your onboard account. Some companies like Princess give passengers the option to pre-tip before they've even set foot aboard, so they don't even have to think about it.

What currency should you tip on a cruise boat?
If you've left an Australian port, our dollars are fine. Anywhere else, no one will say no to a greenback.

source : https://www.escape.com.au/experiences/cruises/ocean/how-much-should-you-be-tipping-on-international-cruises/news-story/0f5cd8464256baffac80a1e5d6308263