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 $89.36   5.264%   $94.0639   $94.06   $94.05   $94.10  
  Purchase #2 $191.94   5.325%   $202.1608   $202.16   $202.15   $202.20  
  Purchase #3 $33.47   5.360%   $35.264   $35.26   $35.25   $35.30  
  Purchase #4 $178.84   11.434%   $199.2886   $199.29   $199.30   $199.30  
  Purchase #5 $218.66   3.622%   $226.5799   $226.58   $226.60   $226.60  
  Purchase #6 $117.50   13.432%   $133.2826   $133.28   $133.30   $133.30  
  Purchase #7 $214.25   13.790%   $243.7951   $243.80   $243.80   $243.80  
  7 purchase totals = $1,044.02       $1,134.4349   $1,134.43   $1,134.45   $1,134.60