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 $92.61   3.394%   $95.7532   $95.75   $95.75   $95.80  
  Purchase #2 $26.94   8.225%   $29.1558   $29.16   $29.15   $29.20  
  Purchase #3 $181.60   12.374%   $204.0712   $204.07   $204.05   $204.10  
  Purchase #4 $211.89   5.771%   $224.1182   $224.12   $224.10   $224.10  
  Purchase #5 $163.47   7.147%   $175.1532   $175.15   $175.15   $175.20  
  Purchase #6 $164.42   3.240%   $169.7472   $169.75   $169.75   $169.70  
  Purchase #7 $167.64   5.215%   $176.3824   $176.38   $176.40   $176.40  
  7 purchase totals = $1,008.57       $1,074.3812   $1,074.38   $1,074.35   $1,074.50