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 $184.89   5.227%   $194.5542   $194.55   $194.55   $194.60  
  Purchase #2 $223.57   5.239%   $235.2828   $235.28   $235.30   $235.30  
  Purchase #3 $204.58   6.706%   $218.2991   $218.30   $218.30   $218.30  
  Purchase #4 $245.92   5.248%   $258.8259   $258.83   $258.85   $258.80  
  Purchase #5 $153.89   7.269%   $165.0763   $165.08   $165.10   $165.10  
  Purchase #6 $36.58   7.867%   $39.4577   $39.46   $39.45   $39.50  
  Purchase #7 $47.25   10.743%   $52.3261   $52.33   $52.35   $52.30  
  7 purchase totals = $1,096.68       $1,163.8221   $1,163.83   $1,163.90   $1,163.90