Let's do some math ..  Rounding examples of 7 random hypothetical purchases:
  Case Tag  
Price  
Sales  
Tax %  
Raw Total  
Incl. Sales Tax  
Rounded  
to Penny  
Rounded  
to Nickel  
Rounded  
to Dime  
  Purchase #1 $216.93   4.275%   $226.2038   $226.20   $226.20   $226.20  
  Purchase #2 $87.51   7.830%   $94.362   $94.36   $94.35   $94.40  
  Purchase #3 $75.43   13.613%   $85.6983   $85.70   $85.70   $85.70  
  Purchase #4 $219.71   12.231%   $246.5827   $246.58   $246.60   $246.60  
  Purchase #5 $195.70   4.551%   $204.6063   $204.61   $204.60   $204.60  
  Purchase #6 $249.49   12.424%   $280.4866   $280.49   $280.50   $280.50  
  Purchase #7 $214.35   4.178%   $223.3055   $223.31   $223.30   $223.30  
  7 purchase totals = $1,259.12       $1,361.2452   $1,361.25   $1,361.25   $1,361.30