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 $43.66   7.534%   $46.9493   $46.95   $46.95   $46.90  
  Purchase #2 $33.88   11.567%   $37.7989   $37.80   $37.80   $37.80  
  Purchase #3 $68.68   11.583%   $76.6352   $76.64   $76.65   $76.60  
  Purchase #4 $115.62   6.830%   $123.5168   $123.52   $123.50   $123.50  
  Purchase #5 $139.57   4.353%   $145.6455   $145.65   $145.65   $145.60  
  Purchase #6 $215.52   7.225%   $231.0913   $231.09   $231.10   $231.10  
  Purchase #7 $103.31   6.527%   $110.053   $110.05   $110.05   $110.10  
  7 purchase totals = $720.24       $771.6900   $771.70   $771.70   $771.60