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 $118.65   5.324%   $124.9669   $124.97   $124.95   $125.00  
  Purchase #2 $210.50   13.374%   $238.6523   $238.65   $238.65   $238.70  
  Purchase #3 $235.69   5.693%   $249.1078   $249.11   $249.10   $249.10  
  Purchase #4 $62.43   9.647%   $68.4526   $68.45   $68.45   $68.50  
  Purchase #5 $180.83   9.524%   $198.0522   $198.05   $198.05   $198.10  
  Purchase #6 $6.76   7.221%   $7.2481   $7.25   $7.25   $7.20  
  Purchase #7 $172.71   5.349%   $181.9483   $181.95   $181.95   $181.90  
  7 purchase totals = $987.57       $1,068.4282   $1,068.43   $1,068.40   $1,068.50