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 $61.59   10.299%   $67.9332   $67.93   $67.95   $67.90  
  Purchase #2 $207.94   12.683%   $234.313   $234.31   $234.30   $234.30  
  Purchase #3 $180.35   6.584%   $192.2242   $192.22   $192.20   $192.20  
  Purchase #4 $150.83   5.336%   $158.8783   $158.88   $158.90   $158.90  
  Purchase #5 $118.77   3.739%   $123.2108   $123.21   $123.20   $123.20  
  Purchase #6 $164.27   6.301%   $174.6207   $174.62   $174.60   $174.60  
  Purchase #7 $161.26   8.391%   $174.7913   $174.79   $174.80   $174.80  
  7 purchase totals = $1,045.01       $1,125.9715   $1,125.96   $1,125.95   $1,125.90