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 $86.81   9.430%   $94.9962   $95.00   $95.00   $95.00  
  Purchase #2 $57.58   10.835%   $63.8188   $63.82   $63.80   $63.80  
  Purchase #3 $31.57   8.303%   $34.1913   $34.19   $34.20   $34.20  
  Purchase #4 $173.59   4.330%   $181.1064   $181.11   $181.10   $181.10  
  Purchase #5 $96.40   8.405%   $104.5024   $104.50   $104.50   $104.50  
  Purchase #6 $241.83   4.575%   $252.8937   $252.89   $252.90   $252.90  
  Purchase #7 $139.40   11.731%   $155.753   $155.75   $155.75   $155.80  
  7 purchase totals = $827.18       $887.2618   $887.26   $887.25   $887.30