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 $119.38   5.272%   $125.6737   $125.67   $125.65   $125.70  
  Purchase #2 $228.26   3.210%   $235.5871   $235.59   $235.60   $235.60  
  Purchase #3 $207.59   6.620%   $221.3325   $221.33   $221.35   $221.30  
  Purchase #4 $25.26   13.532%   $28.6782   $28.68   $28.70   $28.70  
  Purchase #5 $157.64   13.651%   $179.1594   $179.16   $179.15   $179.20  
  Purchase #6 $234.99   4.330%   $245.1651   $245.17   $245.15   $245.20  
  Purchase #7 $178.37   8.126%   $192.8643   $192.86   $192.85   $192.90  
  7 purchase totals = $1,151.49       $1,228.4603   $1,228.46   $1,228.45   $1,228.60