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	$224.61	3.755%	$233.0441	$233.04	$233.05	$233.00
Purchase #2	$10.69	7.353%	$11.476	$11.48	$11.50	$11.50
Purchase #3	$139.37	8.621%	$151.3851	$151.39	$151.40	$151.40
Purchase #4	$249.54	5.438%	$263.11	$263.11	$263.10	$263.10
Purchase #5	$21.92	12.195%	$24.5931	$24.59	$24.60	$24.60
Purchase #6	$147.53	9.326%	$161.2886	$161.29	$161.30	$161.30
Purchase #7	$151.61	13.872%	$172.6413	$172.64	$172.65	$172.60
7 purchase totals =	$945.27		$1,017.5382	$1,017.54	$1,017.60	$1,017.50