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 $193.93   10.348%   $213.9979   $214.00   $214.00   $214.00  
  Purchase #2 $176.78   10.280%   $194.953   $194.95   $194.95   $195.00  
  Purchase #3 $220.47   5.849%   $233.3653   $233.37   $233.35   $233.40  
  Purchase #4 $59.90   8.715%   $65.1203   $65.12   $65.10   $65.10  
  Purchase #5 $244.28   6.870%   $261.062   $261.06   $261.05   $261.10  
  Purchase #6 $236.36   3.160%   $243.829   $243.83   $243.85   $243.80  
  Purchase #7 $218.29   13.476%   $247.7068   $247.71   $247.70   $247.70  
  7 purchase totals = $1,350.01       $1,460.0343   $1,460.04   $1,460.00   $1,460.10