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 $181.68   7.314%   $194.9681   $194.97   $194.95   $195.00  
  Purchase #2 $58.71   6.619%   $62.596   $62.60   $62.60   $62.60  
  Purchase #3 $162.66   10.625%   $179.9426   $179.94   $179.95   $179.90  
  Purchase #4 $162.58   12.515%   $182.9269   $182.93   $182.95   $182.90  
  Purchase #5 $150.68   5.423%   $158.8514   $158.85   $158.85   $158.90  
  Purchase #6 $250.39   8.856%   $272.5645   $272.56   $272.55   $272.60  
  Purchase #7 $17.55   11.221%   $19.5193   $19.52   $19.50   $19.50  
  7 purchase totals = $984.25       $1,071.3688   $1,071.37   $1,071.35   $1,071.40