Modifiers - 3 modifiers with precedence

Line unit price: 5 GBP

I have 3 modifiers:

Modifier 1: .50 GBP volume discount

Modifier 2: .20 GBP volume discount

Modifier 3: 7% discount

All 3 modifiers are to be applied to a particular item in the following order:

Modifer 1 and 2 both apply to the base order line price.

5 - (.5 + .2) = 4.3

4.3 - 7% = 4

Do I need to setup buckets to apply these modifiers in the way I need or is the precedence enough? When I try only using precendence the % applies to the base unit price and not to the unit price less the volume discounts. When I use buckets it applies as I would like. My understanding was that precedence should be enough.