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 $58.81   3.634%   $60.9472   $60.95   $60.95   $60.90  
  Purchase #2 $196.57   9.377%   $215.0024   $215.00   $215.00   $215.00  
  Purchase #3 $93.96   11.559%   $104.8208   $104.82   $104.80   $104.80  
  Purchase #4 $169.29   4.392%   $176.7252   $176.73   $176.75   $176.70  
  Purchase #5 $221.87   3.530%   $229.702   $229.70   $229.70   $229.70  
  Purchase #6 $216.65   8.607%   $235.2971   $235.30   $235.30   $235.30  
  Purchase #7 $172.51   11.577%   $192.4815   $192.48   $192.50   $192.50  
  7 purchase totals = $1,129.66       $1,214.9762   $1,214.98   $1,215.00   $1,214.90