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 $84.28   12.678%   $94.965   $94.97   $94.95   $95.00  
  Purchase #2 $89.57   7.561%   $96.3424   $96.34   $96.35   $96.30  
  Purchase #3 $118.89   13.700%   $135.1779   $135.18   $135.20   $135.20  
  Purchase #4 $242.68   7.714%   $261.4003   $261.40   $261.40   $261.40  
  Purchase #5 $106.80   8.835%   $116.2358   $116.24   $116.25   $116.20  
  Purchase #6 $233.79   13.569%   $265.513   $265.51   $265.50   $265.50  
  Purchase #7 $111.40   3.696%   $115.5173   $115.52   $115.50   $115.50  
  7 purchase totals = $987.41       $1,085.1517   $1,085.16   $1,085.15   $1,085.10