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	$173.29	11.296%	$192.8648	$192.86	$192.85	$192.90
Purchase #2	$59.59	6.269%	$63.3257	$63.33	$63.35	$63.30
Purchase #3	$154.88	10.410%	$171.003	$171.00	$171.00	$171.00
Purchase #4	$176.30	13.689%	$200.4337	$200.43	$200.45	$200.40
Purchase #5	$191.67	13.362%	$217.2809	$217.28	$217.30	$217.30
Purchase #6	$155.40	4.266%	$162.0294	$162.03	$162.05	$162.00
Purchase #7	$14.62	4.754%	$15.315	$15.32	$15.30	$15.30
7 purchase totals =	$925.75		$1,022.2525	$1,022.25	$1,022.30	$1,022.20