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 $61.54   3.465%   $63.6724   $63.67   $63.65   $63.70  
  Purchase #2 $194.44   11.735%   $217.2575   $217.26   $217.25   $217.30  
  Purchase #3 $79.70   8.504%   $86.4777   $86.48   $86.50   $86.50  
  Purchase #4 $88.59   8.615%   $96.222   $96.22   $96.20   $96.20  
  Purchase #5 $136.34   7.630%   $146.7427   $146.74   $146.75   $146.70  
  Purchase #6 $138.28   12.463%   $155.5138   $155.51   $155.50   $155.50  
  Purchase #7 $239.85   8.682%   $260.6738   $260.67   $260.65   $260.70  
  7 purchase totals = $938.74       $1,026.5599   $1,026.55   $1,026.50   $1,026.60