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 $87.43   8.624%   $94.97   $94.97   $94.95   $95.00  
  Purchase #2 $213.48   8.229%   $231.0473   $231.05   $231.05   $231.00  
  Purchase #3 $104.62   9.784%   $114.856   $114.86   $114.85   $114.90  
  Purchase #4 $21.89   6.718%   $23.3606   $23.36   $23.35   $23.40  
  Purchase #5 $109.54   7.718%   $117.9943   $117.99   $118.00   $118.00  
  Purchase #6 $152.80   9.678%   $167.588   $167.59   $167.60   $167.60  
  Purchase #7 $42.52   5.291%   $44.7697   $44.77   $44.75   $44.80  
  7 purchase totals = $732.28       $794.5859   $794.59   $794.55   $794.70