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 $92.91   3.258%   $95.937   $95.94   $95.95   $95.90  
  Purchase #2 $30.88   6.760%   $32.9675   $32.97   $32.95   $33.00  
  Purchase #3 $216.68   10.173%   $238.7229   $238.72   $238.70   $238.70  
  Purchase #4 $212.34   8.263%   $229.8857   $229.89   $229.90   $229.90  
  Purchase #5 $128.79   5.537%   $135.9211   $135.92   $135.90   $135.90  
  Purchase #6 $222.27   8.407%   $240.9562   $240.96   $240.95   $241.00  
  Purchase #7 $117.97   11.528%   $131.5696   $131.57   $131.55   $131.60  
  7 purchase totals = $1,021.84       $1,105.9600   $1,105.97   $1,105.90   $1,106.00