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 $59.32   4.608%   $62.0535   $62.05   $62.05   $62.10  
  Purchase #2 $76.60   7.424%   $82.2868   $82.29   $82.30   $82.30  
  Purchase #3 $33.98   4.673%   $35.5679   $35.57   $35.55   $35.60  
  Purchase #4 $217.56   3.373%   $224.8983   $224.90   $224.90   $224.90  
  Purchase #5 $221.60   6.836%   $236.7486   $236.75   $236.75   $236.70  
  Purchase #6 $249.36   13.195%   $282.2631   $282.26   $282.25   $282.30  
  Purchase #7 $215.45   4.813%   $225.8196   $225.82   $225.80   $225.80  
  7 purchase totals = $1,073.87       $1,149.6378   $1,149.64   $1,149.60   $1,149.70