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	$209.44	11.689%	$233.9214	$233.92	$233.90	$233.90
Purchase #2	$196.51	11.180%	$218.4798	$218.48	$218.50	$218.50
Purchase #3	$155.89	13.272%	$176.5797	$176.58	$176.60	$176.60
Purchase #4	$40.96	3.339%	$42.3277	$42.33	$42.35	$42.30
Purchase #5	$173.40	4.420%	$181.0643	$181.06	$181.05	$181.10
Purchase #6	$32.42	4.480%	$33.8724	$33.87	$33.85	$33.90
Purchase #7	$150.63	5.748%	$159.2882	$159.29	$159.30	$159.30
7 purchase totals =	$959.25		$1,045.5335	$1,045.53	$1,045.55	$1,045.60