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 $87.55   8.622%   $95.0986   $95.10   $95.10   $95.10  
  Purchase #2 $206.25   7.409%   $221.5311   $221.53   $221.55   $221.50  
  Purchase #3 $55.95   6.378%   $59.5185   $59.52   $59.50   $59.50  
  Purchase #4 $140.95   7.364%   $151.3296   $151.33   $151.35   $151.30  
  Purchase #5 $156.37   11.137%   $173.7849   $173.78   $173.80   $173.80  
  Purchase #6 $212.29   6.783%   $226.6896   $226.69   $226.70   $226.70  
  Purchase #7 $239.55   3.431%   $247.769   $247.77   $247.75   $247.80  
  7 purchase totals = $1,098.91       $1,175.7213   $1,175.72   $1,175.75   $1,175.70