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 $44.31   5.455%   $46.7271   $46.73   $46.75   $46.70  
  Purchase #2 $187.60   3.600%   $194.3536   $194.35   $194.35   $194.40  
  Purchase #3 $188.53   6.713%   $201.186   $201.19   $201.20   $201.20  
  Purchase #4 $212.43   5.610%   $224.3473   $224.35   $224.35   $224.30  
  Purchase #5 $100.31   6.235%   $106.5643   $106.56   $106.55   $106.60  
  Purchase #6 $209.70   4.230%   $218.5703   $218.57   $218.55   $218.60  
  Purchase #7 $21.54   4.383%   $22.4841   $22.48   $22.50   $22.50  
  7 purchase totals = $964.42       $1,014.2327   $1,014.23   $1,014.25   $1,014.30