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	$176.89	11.397%	$197.0502	$197.05	$197.05	$197.10
Purchase #2	$93.76	7.230%	$100.5388	$100.54	$100.55	$100.50
Purchase #3	$232.72	10.615%	$257.4232	$257.42	$257.40	$257.40
Purchase #4	$156.29	6.261%	$166.0753	$166.08	$166.10	$166.10
Purchase #5	$142.76	7.195%	$153.0316	$153.03	$153.05	$153.00
Purchase #6	$146.73	3.323%	$151.6058	$151.61	$151.60	$151.60
Purchase #7	$72.32	3.181%	$74.6205	$74.62	$74.60	$74.60
7 purchase totals =	$1,021.47		$1,100.3454	$1,100.35	$1,100.35	$1,100.30