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 $85.81   10.190%   $94.554   $94.55   $94.55   $94.60  
  Purchase #2 $113.36   3.385%   $117.1972   $117.20   $117.20   $117.20  
  Purchase #3 $19.93   12.255%   $22.3724   $22.37   $22.35   $22.40  
  Purchase #4 $149.80   11.178%   $166.5446   $166.54   $166.55   $166.50  
  Purchase #5 $136.51   6.227%   $145.0105   $145.01   $145.00   $145.00  
  Purchase #6 $160.29   6.374%   $170.5069   $170.51   $170.50   $170.50  
  Purchase #7 $15.82   6.507%   $16.8494   $16.85   $16.85   $16.80  
  7 purchase totals = $681.52       $733.0350   $733.03   $733.00   $733.00