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 $179.58   9.673%   $196.9508   $196.95   $196.95   $197.00  
  Purchase #2 $192.99   4.339%   $201.3638   $201.36   $201.35   $201.40  
  Purchase #3 $220.69   6.671%   $235.4122   $235.41   $235.40   $235.40  
  Purchase #4 $192.70   7.822%   $207.773   $207.77   $207.75   $207.80  
  Purchase #5 $219.82   11.361%   $244.7938   $244.79   $244.80   $244.80  
  Purchase #6 $116.94   4.507%   $122.2105   $122.21   $122.20   $122.20  
  Purchase #7 $229.41   10.653%   $253.849   $253.85   $253.85   $253.80  
  7 purchase totals = $1,352.13       $1,462.3531   $1,462.34   $1,462.30   $1,462.40