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 $58.93   5.459%   $62.147   $62.15   $62.15   $62.10  
  Purchase #2 $183.53   5.489%   $193.604   $193.60   $193.60   $193.60  
  Purchase #3 $221.30   12.354%   $248.6394   $248.64   $248.65   $248.60  
  Purchase #4 $86.26   7.561%   $92.7821   $92.78   $92.80   $92.80  
  Purchase #5 $185.64   4.627%   $194.2296   $194.23   $194.25   $194.20  
  Purchase #6 $206.75   13.595%   $234.8577   $234.86   $234.85   $234.90  
  Purchase #7 $243.27   6.815%   $259.8489   $259.85   $259.85   $259.80  
  7 purchase totals = $1,185.68       $1,286.1087   $1,286.11   $1,286.15   $1,286.00