Decimals In Product Price

Who knows how to increase # of decimals in product price?

If I specify "Decimals" more than 2 in currency settings I receive a warning:

"You have specified 4 decimal places for USD. The maximum number of supported decimal places is 2. Further values will be displayed as zeros."

I altered MySQL table 'cscart_currencies' like this:

ALTER TABLE `cscart_currencies`
CHANGE COLUMN `coefficient` `coefficient` DOUBLE(12,4) NOT NULL DEFAULT '1.00000000'

Is that sufficient?

I am afraid, a lot of tables in database store prices in decimal(12,2) format. So it will be required to rework the whole database to use 4 deciamals