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 $43.75   5.140%   $45.9988   $46.00   $46.00   $46.00  
  Purchase #2 $234.39   8.194%   $253.5959   $253.60   $253.60   $253.60  
  Purchase #3 $97.56   5.607%   $103.0302   $103.03   $103.05   $103.00  
  Purchase #4 $200.86   7.540%   $216.0048   $216.00   $216.00   $216.00  
  Purchase #5 $215.74   12.780%   $243.3116   $243.31   $243.30   $243.30  
  Purchase #6 $67.40   3.323%   $69.6397   $69.64   $69.65   $69.60  
  Purchase #7 $177.34   13.145%   $200.6513   $200.65   $200.65   $200.70  
  7 purchase totals = $1,037.04       $1,132.2323   $1,132.23   $1,132.25   $1,132.20