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 $177.96   9.563%   $194.9783   $194.98   $195.00   $195.00  
  Purchase #2 $232.78   11.697%   $260.0083   $260.01   $260.00   $260.00  
  Purchase #3 $35.40   6.296%   $37.6288   $37.63   $37.65   $37.60  
  Purchase #4 $125.35   6.214%   $133.1392   $133.14   $133.15   $133.10  
  Purchase #5 $50.70   4.714%   $53.09   $53.09   $53.10   $53.10  
  Purchase #6 $181.40   4.266%   $189.1385   $189.14   $189.15   $189.10  
  Purchase #7 $128.33   13.834%   $146.0832   $146.08   $146.10   $146.10  
  7 purchase totals = $931.92       $1,014.0663   $1,014.07   $1,014.15   $1,014.00