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 $84.69   12.131%   $94.9637   $94.96   $94.95   $95.00  
  Purchase #2 $234.95   9.482%   $257.228   $257.23   $257.25   $257.20  
  Purchase #3 $167.70   3.489%   $173.5511   $173.55   $173.55   $173.60  
  Purchase #4 $58.97   9.715%   $64.6989   $64.70   $64.70   $64.70  
  Purchase #5 $158.44   11.381%   $176.4721   $176.47   $176.45   $176.50  
  Purchase #6 $242.43   6.731%   $258.748   $258.75   $258.75   $258.70  
  Purchase #7 $200.67   13.685%   $228.1317   $228.13   $228.15   $228.10  
  7 purchase totals = $1,147.85       $1,253.7935   $1,253.79   $1,253.80   $1,253.80