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 $180.70   8.214%   $195.5427   $195.54   $195.55   $195.50  
  Purchase #2 $186.31   7.132%   $199.5976   $199.60   $199.60   $199.60  
  Purchase #3 $62.80   3.496%   $64.9955   $65.00   $65.00   $65.00  
  Purchase #4 $167.80   6.350%   $178.4553   $178.46   $178.45   $178.50  
  Purchase #5 $185.65   9.693%   $203.6451   $203.65   $203.65   $203.60  
  Purchase #6 $163.65   9.350%   $178.9513   $178.95   $178.95   $179.00  
  Purchase #7 $72.56   4.261%   $75.6518   $75.65   $75.65   $75.70  
  7 purchase totals = $1,019.47       $1,096.8393   $1,096.85   $1,096.85   $1,096.90