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 $56.95   9.479%   $62.3483   $62.35   $62.35   $62.30  
  Purchase #2 $166.54   10.653%   $184.2815   $184.28   $184.30   $184.30  
  Purchase #3 $85.64   7.326%   $91.914   $91.91   $91.90   $91.90  
  Purchase #4 $186.93   12.633%   $210.5449   $210.54   $210.55   $210.50  
  Purchase #5 $151.90   12.273%   $170.5427   $170.54   $170.55   $170.50  
  Purchase #6 $195.56   10.302%   $215.7066   $215.71   $215.70   $215.70  
  Purchase #7 $204.91   6.716%   $218.6718   $218.67   $218.65   $218.70  
  7 purchase totals = $1,048.43       $1,154.0098   $1,154.00   $1,154.00   $1,153.90