You don't want simpler, you probably need more complex. Invocing is a complex field that requires a good bit of accounting knowledge (knowledge of internal controls to prevent fraud in particular and how those would be implemented in your database).
But lets start with a simple example, customers do not have only 1 address (or ship to only one address), so you should have a separate address table. You should have a separate phone table. You should have lookup tables for phone types and address types. You probably need product lookup tables.
I can't say for sure in mysql, but float is generally an inexact datatype and should not be used for any number you intend to do calclutions with. Not unless you like dealing with rounding errors. Or losing money. Accountants tend to hate that kind of thing.
Shipping address should be linked to the invoice not the customer. I may ship one order to a customer in Maine one day and another to a differnt person in Washington the next. I may ship to any one of my three offices or to my home or to my parent's home.
How are you planning to maintain those updated by and updated date fields? They shoudl be in a trigger or they are useless.
Normally products have some sort of product details that can vary such as color or size or no of items in the package. You have a description field for this but 80 chazractesr seems way too small to me.
Truly you need to learn normalization before you even attempt to design a database, let alone one with serious legal implications.
Taxes can be quite difficult depending on how many states or countries you are selling to and the typesof products you sell. Without knowing more detatils it is imposooible to design a good set of tables for taxes. There is no way under the sun that I would consider deigning such a thing without consultations with a good experienced accountant. Preferably one with auditing experience.
There are many many professionally designed accounting packages that do invoicing, it would be cheaper and far better from a legal standpoint to buy one.