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 $58.58   7.453%   $62.946   $62.95   $62.95   $62.90  
  Purchase #2 $116.96   7.523%   $125.7589   $125.76   $125.75   $125.80  
  Purchase #3 $74.95   6.849%   $80.0833   $80.08   $80.10   $80.10  
  Purchase #4 $88.53   4.826%   $92.8025   $92.80   $92.80   $92.80  
  Purchase #5 $41.90   5.794%   $44.3277   $44.33   $44.35   $44.30  
  Purchase #6 $150.69   12.513%   $169.5458   $169.55   $169.55   $169.50  
  Purchase #7 $105.27   11.488%   $117.3634   $117.36   $117.35   $117.40  
  7 purchase totals = $636.88       $692.8276   $692.83   $692.85   $692.80