Hi there, @wyrdbyrd !
First of all, I want to say congratulations on your first order! This is such an exciting time 
I’m happy to look into your tax question with you.
Can you confirm whether there were multiple items in this order? I ask this because on Shopify, tax amounts are rounded at the line-item level. This means that the total tax value is calculated by applying the tax rate to each line in the order, rounding the results, and then adding these subtotals together to arrive at the total value of the order. The result of this is sometimes the tax amount is different than what it would have been if it was applied to the total order amount. You can read more about tax rounding in this help document.
If you’d like to share the items in this order as well as their prices I can definitely take a look and see whether the tax amount makes sense.
I look forward to helping you further!