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 $181.94   7.666%   $195.8875   $195.89   $195.90   $195.90  
  Purchase #2 $247.56   6.515%   $263.6885   $263.69   $263.70   $263.70  
  Purchase #3 $110.84   7.323%   $118.9568   $118.96   $118.95   $119.00  
  Purchase #4 $226.60   13.371%   $256.8987   $256.90   $256.90   $256.90  
  Purchase #5 $55.41   5.405%   $58.4049   $58.40   $58.40   $58.40  
  Purchase #6 $7.41   8.252%   $8.0215   $8.02   $8.00   $8.00  
  Purchase #7 $55.53   8.206%   $60.0868   $60.09   $60.10   $60.10  
  7 purchase totals = $885.29       $961.9447   $961.95   $961.95   $962.00