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 $195.74   3.310%   $202.219   $202.22   $202.20   $202.20  
  Purchase #2 $220.70   5.738%   $233.3638   $233.36   $233.35   $233.40  
  Purchase #3 $208.71   4.583%   $218.2752   $218.28   $218.30   $218.30  
  Purchase #4 $188.95   3.485%   $195.5349   $195.53   $195.55   $195.50  
  Purchase #5 $152.25   4.636%   $159.3083   $159.31   $159.30   $159.30  
  Purchase #6 $54.39   9.684%   $59.6571   $59.66   $59.65   $59.70  
  Purchase #7 $24.95   4.839%   $26.1573   $26.16   $26.15   $26.20  
  7 purchase totals = $1,045.69       $1,094.5156   $1,094.52   $1,094.50   $1,094.60