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 $216.98   9.269%   $237.0919   $237.09   $237.10   $237.10  
  Purchase #2 $157.59   13.478%   $178.83   $178.83   $178.85   $178.80  
  Purchase #3 $84.82   13.195%   $96.012   $96.01   $96.00   $96.00  
  Purchase #4 $81.51   8.477%   $88.4196   $88.42   $88.40   $88.40  
  Purchase #5 $205.65   4.142%   $214.168   $214.17   $214.15   $214.20  
  Purchase #6 $234.35   4.197%   $244.1857   $244.19   $244.20   $244.20  
  Purchase #7 $132.25   7.658%   $142.3777   $142.38   $142.40   $142.40  
  7 purchase totals = $1,113.15       $1,201.0849   $1,201.09   $1,201.10   $1,201.10