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 $195.42   8.330%   $211.6985   $211.70   $211.70   $211.70  
  Purchase #2 $27.74   3.206%   $28.6293   $28.63   $28.65   $28.60  
  Purchase #3 $178.79   10.788%   $198.0779   $198.08   $198.10   $198.10  
  Purchase #4 $186.94   3.351%   $193.2044   $193.20   $193.20   $193.20  
  Purchase #5 $139.78   8.234%   $151.2895   $151.29   $151.30   $151.30  
  Purchase #6 $211.28   4.555%   $220.9038   $220.90   $220.90   $220.90  
  Purchase #7 $188.53   5.304%   $198.5296   $198.53   $198.55   $198.50  
  7 purchase totals = $1,128.48       $1,202.3330   $1,202.33   $1,202.40   $1,202.30