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 $113.47   10.775%   $125.6964   $125.70   $125.70   $125.70  
  Purchase #2 $188.98   9.651%   $207.2185   $207.22   $207.20   $207.20  
  Purchase #3 $216.82   7.664%   $233.4371   $233.44   $233.45   $233.40  
  Purchase #4 $189.37   7.791%   $204.1238   $204.12   $204.10   $204.10  
  Purchase #5 $206.39   4.163%   $214.982   $214.98   $215.00   $215.00  
  Purchase #6 $206.56   11.175%   $229.6431   $229.64   $229.65   $229.60  
  Purchase #7 $197.94   11.369%   $220.4438   $220.44   $220.45   $220.40  
  7 purchase totals = $1,319.53       $1,435.5447   $1,435.54   $1,435.55   $1,435.40