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	$211.33	3.829%	$219.4218	$219.42	$219.40	$219.40
Purchase #2	$67.31	9.379%	$73.623	$73.62	$73.60	$73.60
Purchase #3	$234.45	8.188%	$253.6468	$253.65	$253.65	$253.60
Purchase #4	$106.62	12.532%	$119.9816	$119.98	$120.00	$120.00
Purchase #5	$53.38	11.445%	$59.4893	$59.49	$59.50	$59.50
Purchase #6	$183.71	3.785%	$190.6634	$190.66	$190.65	$190.70
Purchase #7	$226.67	10.499%	$250.4681	$250.47	$250.45	$250.50
7 purchase totals =	$1,083.47		$1,167.2940	$1,167.29	$1,167.25	$1,167.30