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 $69.72   9.279%   $76.1893   $76.19   $76.20   $76.20  
  Purchase #2 $213.40   9.478%   $233.6261   $233.63   $233.65   $233.60  
  Purchase #3 $60.64   3.308%   $62.646   $62.65   $62.65   $62.60  
  Purchase #4 $54.87   6.211%   $58.278   $58.28   $58.30   $58.30  
  Purchase #5 $205.97   5.188%   $216.6557   $216.66   $216.65   $216.70  
  Purchase #6 $240.66   13.860%   $274.0155   $274.02   $274.00   $274.00  
  Purchase #7 $199.30   11.538%   $222.2952   $222.30   $222.30   $222.30  
  7 purchase totals = $1,044.56       $1,143.7058   $1,143.73   $1,143.75   $1,143.70