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 $61.81   3.132%   $63.7459   $63.75   $63.75   $63.70  
  Purchase #2 $169.64   4.538%   $177.3383   $177.34   $177.35   $177.30  
  Purchase #3 $160.67   7.122%   $172.1129   $172.11   $172.10   $172.10  
  Purchase #4 $184.95   10.146%   $203.715   $203.72   $203.70   $203.70  
  Purchase #5 $216.67   3.742%   $224.7778   $224.78   $224.80   $224.80  
  Purchase #6 $199.56   3.732%   $207.0076   $207.01   $207.00   $207.00  
  Purchase #7 $40.34   9.752%   $44.274   $44.27   $44.25   $44.30  
  7 purchase totals = $1,033.64       $1,092.9715   $1,092.98   $1,092.95   $1,092.90