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 $243.61   7.650%   $262.2462   $262.25   $262.25   $262.20  
  Purchase #2 $100.61   13.290%   $113.9811   $113.98   $114.00   $114.00  
  Purchase #3 $209.86   12.118%   $235.2908   $235.29   $235.30   $235.30  
  Purchase #4 $223.77   4.559%   $233.9717   $233.97   $233.95   $234.00  
  Purchase #5 $114.31   6.288%   $121.4978   $121.50   $121.50   $121.50  
  Purchase #6 $152.75   7.496%   $164.2001   $164.20   $164.20   $164.20  
  Purchase #7 $181.47   13.519%   $206.0029   $206.00   $206.00   $206.00  
  7 purchase totals = $1,226.38       $1,337.1906   $1,337.19   $1,337.20   $1,337.20