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 $23.52   11.155%   $26.1437   $26.14   $26.15   $26.10  
  Purchase #2 $197.89   11.188%   $220.0299   $220.03   $220.05   $220.00  
  Purchase #3 $129.71   3.170%   $133.8218   $133.82   $133.80   $133.80  
  Purchase #4 $204.68   3.536%   $211.9175   $211.92   $211.90   $211.90  
  Purchase #5 $146.32   4.188%   $152.4479   $152.45   $152.45   $152.40  
  Purchase #6 $219.49   4.305%   $228.939   $228.94   $228.95   $228.90  
  Purchase #7 $153.35   5.399%   $161.6294   $161.63   $161.65   $161.60  
  7 purchase totals = $1,074.96       $1,134.9292   $1,134.93   $1,134.95   $1,134.70