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 $90.45   5.309%   $95.252   $95.25   $95.25   $95.30  
  Purchase #2 $85.51   11.447%   $95.2983   $95.30   $95.30   $95.30  
  Purchase #3 $147.34   12.428%   $165.6514   $165.65   $165.65   $165.70  
  Purchase #4 $228.64   7.743%   $246.3436   $246.34   $246.35   $246.30  
  Purchase #5 $85.33   3.810%   $88.5811   $88.58   $88.60   $88.60  
  Purchase #6 $213.59   10.365%   $235.7286   $235.73   $235.75   $235.70  
  Purchase #7 $198.77   9.534%   $217.7207   $217.72   $217.70   $217.70  
  7 purchase totals = $1,049.63       $1,144.5757   $1,144.57   $1,144.60   $1,144.60