"I can't believe the support we've been getting from people we've never even met. We're so grateful," she said.
The family will leave for Los Angeles on March 4, where Tama will undergo a three-week course of intensive therapy.
"Hopefully we'll be able to find a place close to the centre. We thought we could rely on public transport to get to the centre, but they've told us the public transport system there isn't good enough and we'd have to hire a car.
"The extra money pledged on our Givealittle page will help with that, which is lucky because we weren't counting on the extra expense," Mrs Trueman said.
The local community came together over the last couple of days to set up today's "Tamathon" fundraising event in Whakamaru, with the community donating equipment and raffle prizes, and putting up the stalls and children's rides.
"We're a close-knit community around here, and we always try to help each other out; yesterday morning Tama, his brother and his father shaved their heads to help raise funds for [a Mangakino woman] who's got cancer," she said.
Mrs Trueman said the family was overwhelmed by the public's response and wanted to thank everybody for their generous support and donations.