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 $84.48   12.464%   $95.0096   $95.01   $95.00   $95.00  
  Purchase #2 $27.50   5.709%   $29.07   $29.07   $29.05   $29.10  
  Purchase #3 $169.81   5.161%   $178.5739   $178.57   $178.55   $178.60  
  Purchase #4 $216.81   4.852%   $227.3296   $227.33   $227.35   $227.30  
  Purchase #5 $141.46   12.113%   $158.595   $158.60   $158.60   $158.60  
  Purchase #6 $169.74   8.274%   $183.7843   $183.78   $183.80   $183.80  
  Purchase #7 $164.29   10.781%   $182.0021   $182.00   $182.00   $182.00  
  7 purchase totals = $974.09       $1,054.3645   $1,054.36   $1,054.35   $1,054.40