When traveling in the USA, I can purchase an add on for minutes. I can ignore calls I don't want to answer.
How do I prevent paying for text messages if I leave my phone on for traveling in USA and don't want to receive text messages
I don't think there is a way to prevent receiving texts besides actually blocking a contact. I think the only way is to put your phone on airplane mode or turn off cell service but then this would defeat the purpose of having a call booster. You could just tell people not to send texts unless an emergency before you leave or purchase one of the US texting add-ons.
Instead I'd suggest getting your phone unlocked then pick up a pre-paid T-Mobile SIM.
It means everyone that calls/TXT's your # while you're away won't get a response though.
It what I do.
Then to call/TXT back to Canada while in the US, I use the Google Voice App - free/unlimited calls to/from Canada & the US while in Canada/US. Only thing it needs is Data (Mobile or Wi-Fi), but it's pretty minimal since it's only voice & text.