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 $207.98   5.394%   $219.1984   $219.20   $219.20   $219.20  
  Purchase #2 $31.49   11.825%   $35.2137   $35.21   $35.20   $35.20  
  Purchase #3 $93.71   9.410%   $102.5281   $102.53   $102.55   $102.50  
  Purchase #4 $64.38   11.433%   $71.7406   $71.74   $71.75   $71.70  
  Purchase #5 $191.28   6.299%   $203.3287   $203.33   $203.35   $203.30  
  Purchase #6 $208.28   5.201%   $219.1126   $219.11   $219.10   $219.10  
  Purchase #7 $231.93   5.451%   $244.5725   $244.57   $244.55   $244.60  
  7 purchase totals = $1,029.05       $1,095.6946   $1,095.69   $1,095.70   $1,095.60