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 $87.85   8.835%   $95.6115   $95.61   $95.60   $95.60  
  Purchase #2 $234.48   4.584%   $245.2286   $245.23   $245.25   $245.20  
  Purchase #3 $109.85   7.417%   $117.9976   $118.00   $118.00   $118.00  
  Purchase #4 $18.25   9.740%   $20.0276   $20.03   $20.05   $20.00  
  Purchase #5 $145.45   3.486%   $150.5204   $150.52   $150.50   $150.50  
  Purchase #6 $112.39   3.874%   $116.744   $116.74   $116.75   $116.70  
  Purchase #7 $244.78   7.275%   $262.5877   $262.59   $262.60   $262.60  
  7 purchase totals = $953.05       $1,008.7174   $1,008.72   $1,008.75   $1,008.60