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 $58.84   5.337%   $61.9803   $61.98   $62.00   $62.00  
  Purchase #2 $175.32   7.602%   $188.6478   $188.65   $188.65   $188.60  
  Purchase #3 $233.57   8.439%   $253.281   $253.28   $253.30   $253.30  
  Purchase #4 $136.58   10.824%   $151.3634   $151.36   $151.35   $151.40  
  Purchase #5 $235.71   10.658%   $260.832   $260.83   $260.85   $260.80  
  Purchase #6 $67.32   7.658%   $72.4754   $72.48   $72.50   $72.50  
  Purchase #7 $106.36   13.121%   $120.3155   $120.32   $120.30   $120.30  
  7 purchase totals = $1,013.70       $1,108.8954   $1,108.90   $1,108.95   $1,108.90