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 $92.46   9.502%   $101.2455   $101.25   $101.25   $101.20  
  Purchase #2 $245.94   9.500%   $269.3043   $269.30   $269.30   $269.30  
  Purchase #3 $238.50   6.233%   $253.3657   $253.37   $253.35   $253.40  
  Purchase #4 $175.78   11.422%   $195.8576   $195.86   $195.85   $195.90  
  Purchase #5 $163.28   4.302%   $170.3043   $170.30   $170.30   $170.30  
  Purchase #6 $248.52   4.779%   $260.3968   $260.40   $260.40   $260.40  
  Purchase #7 $189.43   11.685%   $211.5649   $211.56   $211.55   $211.60  
  7 purchase totals = $1,353.91       $1,462.0391   $1,462.04   $1,462.00   $1,462.10