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 $85.95   11.571%   $95.8953   $95.90   $95.90   $95.90  
  Purchase #2 $250.56   3.654%   $259.7155   $259.72   $259.70   $259.70  
  Purchase #3 $249.37   10.759%   $276.1997   $276.20   $276.20   $276.20  
  Purchase #4 $231.31   5.464%   $243.9488   $243.95   $243.95   $243.90  
  Purchase #5 $80.59   4.686%   $84.3664   $84.37   $84.35   $84.40  
  Purchase #6 $14.29   12.279%   $16.0447   $16.04   $16.05   $16.00  
  Purchase #7 $113.98   4.244%   $118.8173   $118.82   $118.80   $118.80  
  7 purchase totals = $1,026.05       $1,094.9877   $1,095.00   $1,094.95   $1,094.90