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 $202.46   5.702%   $214.0043   $214.00   $214.00   $214.00  
  Purchase #2 $59.70   5.623%   $63.0569   $63.06   $63.05   $63.10  
  Purchase #3 $144.56   8.626%   $157.0297   $157.03   $157.05   $157.00  
  Purchase #4 $211.59   6.368%   $225.0641   $225.06   $225.05   $225.10  
  Purchase #5 $39.73   7.336%   $42.6446   $42.64   $42.65   $42.60  
  Purchase #6 $159.66   11.140%   $177.4461   $177.45   $177.45   $177.40  
  Purchase #7 $126.87   6.788%   $135.4819   $135.48   $135.50   $135.50  
  7 purchase totals = $944.57       $1,014.7276   $1,014.72   $1,014.75   $1,014.70