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 $181.88   7.395%   $195.33   $195.33   $195.35   $195.30  
  Purchase #2 $192.48   7.222%   $206.3809   $206.38   $206.40   $206.40  
  Purchase #3 $131.69   4.602%   $137.7504   $137.75   $137.75   $137.80  
  Purchase #4 $165.26   6.847%   $176.5754   $176.58   $176.60   $176.60  
  Purchase #5 $59.52   9.674%   $65.278   $65.28   $65.30   $65.30  
  Purchase #6 $127.62   11.414%   $142.1865   $142.19   $142.20   $142.20  
  Purchase #7 $162.79   5.480%   $171.7109   $171.71   $171.70   $171.70  
  7 purchase totals = $1,021.24       $1,095.2121   $1,095.22   $1,095.30   $1,095.30