I check my code coverage of trigger is 100%, apex class is 100%, but need to check my trigger fucntion is correct or not.Plz help.
--------------
trigger: 

trigger PenDiscountRangeTrigger on Parker_pen__C(before insert)
{
 PenDiscountRangeClass.ApplyDiscount(trigger.new);
}
------
apex class:
public class PenDiscountRangeClass{
public static void ApplyDiscount(list<Parker_pen__C> VarPenList)
{
for(Parker_pen__C VarP: VarPenList)
{
if (VarP.Price__c>=100)
{
VarP.Price__c = VarP.Price__c- 30;
}

else if (VarP.Price__c<100 && VarP.Price__c>= 70)
{
VarP.Price__c= VarP.Price__c- 20;
}

else if (VarP.Price__c<70 && VarP.Price__c>= 40)
{
VarP.Price__c= VarP.Price__c- 10;
}

else if (VarP.Price__c<40)
{
VarP.Price__c= VarP.Price__c- 5;
}
}
}
}
----
Test class:
@isTest
class PenDiscountRangeClassTest {
@isTest
static void ApplyDiscountA()
{
 //create record
    Parker_pen__C VarP= New Parker_pen__C();
    VarP.Name='Govind';
    VarP.Price__c=101;
    //insert record
    insert VarP;
    
 //trigger called
   //add new box with new value
     Parker_pen__C VarP2= New Parker_pen__C();
    VarP2= [select price__c from Parker_Pen__C where id=: VarP.id];
    
    //check new value is expected value
    system.assertEquals(71, VarP2.Price__C);
}        
    @isTest
static void ApplyDiscountB()
{
    //create record
    Parker_pen__C VarP= New Parker_pen__C();
    VarP.Name='Govind';
    VarP.Price__c=71;
    //insert record
    insert VarP;
    
   //trigger called
   //add new box with new value
     Parker_pen__C VarP2= New Parker_pen__C();
    VarP2= [select price__c from Parker_Pen__C where id=: VarP.id];
    
    //check new value is expected value
    system.assertEquals(51, VarP2.Price__C);
}        
     @isTest
static void ApplyDiscountC()
{
    //create record
    Parker_pen__C VarP= New Parker_pen__C();
    VarP.Name='Govind';
    VarP.Price__c=40;
    //insert record
    insert VarP;
    
   //trigger called
   //add new box with new value
     Parker_pen__C VarP2= New Parker_pen__C();
    VarP2= [select price__c from Parker_Pen__C where id=: VarP.id];
    
    //check new value is expected value
    system.assertEquals(30, VarP2.Price__C);
}        
     @isTest
static void ApplyDiscountD()
{
    //create record
    Parker_pen__C VarP= New Parker_pen__C();
    VarP.Name='Govind';
    VarP.Price__c=30;
    //insert record
    insert VarP;
    
   //trigger called
   //add new box with new value
     Parker_pen__C VarP2= New Parker_pen__C();
    VarP2= [select price__c from Parker_Pen__C where id=: VarP.id];
    
    //check new value is expected value
    system.assertEquals(25, VarP2.Price__C);
}        
}