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 $57.50   9.482%   $62.9522   $62.95   $62.95   $63.00  
  Purchase #2 $171.30   6.230%   $181.972   $181.97   $181.95   $182.00  
  Purchase #3 $245.46   10.829%   $272.0409   $272.04   $272.05   $272.00  
  Purchase #4 $181.77   11.831%   $203.2752   $203.28   $203.30   $203.30  
  Purchase #5 $206.71   10.617%   $228.6564   $228.66   $228.65   $228.70  
  Purchase #6 $244.30   10.428%   $269.7756   $269.78   $269.80   $269.80  
  Purchase #7 $245.44   8.437%   $266.1478   $266.15   $266.15   $266.10  
  7 purchase totals = $1,352.48       $1,484.8201   $1,484.83   $1,484.85   $1,484.90