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 $46.26   5.196%   $48.6637   $48.66   $48.65   $48.70  
  Purchase #2 $194.82   3.573%   $201.7809   $201.78   $201.80   $201.80  
  Purchase #3 $219.45   4.741%   $229.8541   $229.85   $229.85   $229.90  
  Purchase #4 $244.53   9.503%   $267.7677   $267.77   $267.75   $267.80  
  Purchase #5 $241.95   12.710%   $272.7018   $272.70   $272.70   $272.70  
  Purchase #6 $86.26   11.623%   $96.286   $96.29   $96.30   $96.30  
  Purchase #7 $207.78   13.690%   $236.2251   $236.23   $236.25   $236.20  
  7 purchase totals = $1,241.05       $1,353.2793   $1,353.28   $1,353.30   $1,353.40