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 $85.67   10.867%   $94.9798   $94.98   $95.00   $95.00  
  Purchase #2 $161.58   3.559%   $167.3306   $167.33   $167.35   $167.30  
  Purchase #3 $60.41   9.251%   $65.9985   $66.00   $66.00   $66.00  
  Purchase #4 $246.85   7.776%   $266.0451   $266.05   $266.05   $266.00  
  Purchase #5 $184.81   7.300%   $198.3011   $198.30   $198.30   $198.30  
  Purchase #6 $209.84   8.193%   $227.0322   $227.03   $227.05   $227.00  
  Purchase #7 $34.39   10.758%   $38.0897   $38.09   $38.10   $38.10  
  7 purchase totals = $983.55       $1,057.7770   $1,057.78   $1,057.85   $1,057.70