It would be great to have up to 4 decimal places (both in values and prices).
Certain values don't work properly as for an item of $25 you CAN enter 22.73 (plus 10% GST gives $25). But as soon as you enter a quantity of 3 for example, the total comes to $75.01.
(And changing the value to 22.72 gives $74.98)
Being able to enter 22.7273 would fix this problem