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 $59.38   5.375%   $62.5717   $62.57   $62.55   $62.60  
  Purchase #2 $236.28   9.238%   $258.1075   $258.11   $258.10   $258.10  
  Purchase #3 $14.39   6.648%   $15.3466   $15.35   $15.35   $15.30  
  Purchase #4 $59.82   6.731%   $63.8465   $63.85   $63.85   $63.80  
  Purchase #5 $157.97   4.699%   $165.393   $165.39   $165.40   $165.40  
  Purchase #6 $204.48   6.456%   $217.6812   $217.68   $217.70   $217.70  
  Purchase #7 $237.72   12.483%   $267.3946   $267.39   $267.40   $267.40  
  7 purchase totals = $970.04       $1,050.3411   $1,050.34   $1,050.35   $1,050.30