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 $64.75   6.539%   $68.984   $68.98   $69.00   $69.00  
  Purchase #2 $225.55   5.139%   $237.141   $237.14   $237.15   $237.10  
  Purchase #3 $124.69   11.709%   $139.29   $139.29   $139.30   $139.30  
  Purchase #4 $233.97   3.186%   $241.4243   $241.42   $241.40   $241.40  
  Purchase #5 $233.38   12.767%   $263.1756   $263.18   $263.20   $263.20  
  Purchase #6 $53.98   5.343%   $56.8642   $56.86   $56.85   $56.90  
  Purchase #7 $84.74   3.554%   $87.7517   $87.75   $87.75   $87.80  
  7 purchase totals = $1,021.06       $1,094.6308   $1,094.62   $1,094.65   $1,094.70