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 $183.49   6.745%   $195.8664   $195.87   $195.85   $195.90  
  Purchase #2 $236.64   12.535%   $266.3028   $266.30   $266.30   $266.30  
  Purchase #3 $168.80   8.264%   $182.7496   $182.75   $182.75   $182.70  
  Purchase #4 $246.43   5.650%   $260.3533   $260.35   $260.35   $260.40  
  Purchase #5 $180.44   8.823%   $196.3602   $196.36   $196.35   $196.40  
  Purchase #6 $201.27   11.197%   $223.8062   $223.81   $223.80   $223.80  
  Purchase #7 $160.49   5.415%   $169.1805   $169.18   $169.20   $169.20  
  7 purchase totals = $1,377.56       $1,494.6190   $1,494.62   $1,494.60   $1,494.70