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 $195.36   5.525%   $206.1536   $206.15   $206.15   $206.20  
  Purchase #2 $177.29   5.269%   $186.6314   $186.63   $186.65   $186.60  
  Purchase #3 $50.70   6.567%   $54.0295   $54.03   $54.05   $54.00  
  Purchase #4 $88.52   6.830%   $94.5659   $94.57   $94.55   $94.60  
  Purchase #5 $235.70   5.472%   $248.5975   $248.60   $248.60   $248.60  
  Purchase #6 $218.50   6.594%   $232.9079   $232.91   $232.90   $232.90  
  Purchase #7 $69.96   4.311%   $72.976   $72.98   $73.00   $73.00  
  7 purchase totals = $1,036.03       $1,095.8618   $1,095.87   $1,095.90   $1,095.90