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 $214.30   7.171%   $229.6675   $229.67   $229.65   $229.70  
  Purchase #2 $77.34   8.582%   $83.9773   $83.98   $84.00   $84.00  
  Purchase #3 $89.30   10.309%   $98.5059   $98.51   $98.50   $98.50  
  Purchase #4 $146.66   4.376%   $153.0778   $153.08   $153.10   $153.10  
  Purchase #5 $182.62   7.177%   $195.7266   $195.73   $195.75   $195.70  
  Purchase #6 $167.39   8.523%   $181.6566   $181.66   $181.65   $181.70  
  Purchase #7 $143.47   6.475%   $152.7597   $152.76   $152.75   $152.80  
  7 purchase totals = $1,021.08       $1,095.3714   $1,095.39   $1,095.40   $1,095.50