Module money 

Structs

MinorUnits

Functions

apply_rate

Apply a percent rate to a base. Shared by tax_amount and discount math.

line_total

Compute line total in minor units: qty * unit_price.

line_total_discounted

Line total after applying at most one of (rate discount, fixed discount). If both are set, rate wins — caller should enforce mutual exclusion at the CLI layer. Result is clamped at zero so a mis-sized fixed discount can’t flip the line negative.

tax_amount

Compute tax amount in minor units: base * rate / 100.