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 $63.95   8.624%   $69.465   $69.47   $69.45   $69.50  
  Purchase #2 $233.60   4.520%   $244.1587   $244.16   $244.15   $244.20  
  Purchase #3 $169.96   8.570%   $184.5256   $184.53   $184.55   $184.50  
  Purchase #4 $88.52   5.266%   $93.1815   $93.18   $93.20   $93.20  
  Purchase #5 $100.56   6.862%   $107.4604   $107.46   $107.45   $107.50  
  Purchase #6 $193.97   4.363%   $202.4329   $202.43   $202.45   $202.40  
  Purchase #7 $48.53   4.540%   $50.7333   $50.73   $50.75   $50.70  
  7 purchase totals = $899.09       $951.9574   $951.96   $952.00   $952.00