Is it possible in Magento to charge no tax when a order below $4.50 is placed. It's a bakery and certain products are excepted.
certain products are excepted.
Then assign a different tax class to these products and configure tax rates to be 0% for this tax class.
This is assuming that two $4.00 tax free products are still tax free and the tax is not based on the order.
You can have different tax classes and associate each product with different tax classes (its under the price tab in the products configuration). Just associate products which don't have taxes to "none" in the tax class option.
The business I work for has taxable and non-taxable products, no coding is needed to manage that, Magento already has the needed options.