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 $213.86   4.600%   $223.6976   $223.70   $223.70   $223.70  
  Purchase #2 $194.59   5.289%   $204.8819   $204.88   $204.90   $204.90  
  Purchase #3 $219.59   11.200%   $244.1841   $244.18   $244.20   $244.20  
  Purchase #4 $234.92   12.158%   $263.4816   $263.48   $263.50   $263.50  
  Purchase #5 $159.70   9.708%   $175.2037   $175.20   $175.20   $175.20  
  Purchase #6 $162.93   4.286%   $169.9132   $169.91   $169.90   $169.90  
  Purchase #7 $70.34   13.112%   $79.563   $79.56   $79.55   $79.60  
  7 purchase totals = $1,255.93       $1,360.9251   $1,360.91   $1,360.95   $1,361.00