Do not use float for price

For storing prices, it is not advised to use float because of the possible rounding errors.

For example, storing a price like 3.5 can be stored in a float like 3.4999999.

This will be rounded to 3.5 without any problem with number formating functions.

Still, if you multiply this amount by a large value say 10000, you'll end with a total price of 34999.99 which is off by one cent...

Not a big deal but that's not what's is expected at all. Missing cents can be hard to explain to management as well...

Store prices as INTEGER in cents.

Actually the best way is to use DECIMAL data types with a fixed number of decimal places or some other CURRENCY like data type on databases that support it.

for someone using this to learn, How would I implement DECIMAL correctly?

Regards

DECIMAL is just another type of number field. You can declare the number of decimal places you want to use for DECIMAL numbers.

dev.mysql.com/doc/refman/5.1/en/pre ...