SHIPPING PRICE

 I want to make stored Procedure that get sum total of the order and return the ship price
this is my table:
in my procedure I want to get the order subTotal and return the ship price
For example if the subTotal is 60$ than return  300$
etc,
my problem is that if the "toPrice" = 0, than its mean "higher than"
How can I Write this Code, here is my try:

declare @subTotal int
set @subTotal = 60


SELECT [ShippingPolicyId]
      ,[Header]
      ,[fromPrice]
      ,[toPrice],[price]
  FROM [dbo].[xxx_ShippingPolicy]
where @subTotal >=[fromPrice] and    @subTotal <= [toPrice]
--where @subTotal >=[fromPrice] and case when [toPrice] > 0 then   @subTotal <= [toPrice] else 1=1