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 $44.39   4.864%   $46.5491   $46.55   $46.55   $46.50  
  Purchase #2 $213.75   5.617%   $225.7563   $225.76   $225.75   $225.80  
  Purchase #3 $247.52   8.725%   $269.1161   $269.12   $269.10   $269.10  
  Purchase #4 $238.31   6.181%   $253.0399   $253.04   $253.05   $253.00  
  Purchase #5 $116.77   11.657%   $130.3819   $130.38   $130.40   $130.40  
  Purchase #6 $113.86   3.615%   $117.976   $117.98   $118.00   $118.00  
  Purchase #7 $152.83   12.640%   $172.1477   $172.15   $172.15   $172.10  
  7 purchase totals = $1,127.43       $1,214.9670   $1,214.98   $1,215.00   $1,214.90