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 $118.48   5.698%   $125.231   $125.23   $125.25   $125.20  
  Purchase #2 $235.53   4.316%   $245.6955   $245.70   $245.70   $245.70  
  Purchase #3 $240.47   12.623%   $270.8245   $270.82   $270.80   $270.80  
  Purchase #4 $96.57   11.475%   $107.6514   $107.65   $107.65   $107.70  
  Purchase #5 $110.77   4.661%   $115.933   $115.93   $115.95   $115.90  
  Purchase #6 $55.52   4.452%   $57.9918   $57.99   $58.00   $58.00  
  Purchase #7 $207.35   10.186%   $228.4707   $228.47   $228.45   $228.50  
  7 purchase totals = $1,064.69       $1,151.7979   $1,151.79   $1,151.80   $1,151.80