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	$65.40	7.849%	$70.5332	$70.53	$70.55	$70.50
Purchase #2	$216.62	3.636%	$224.4963	$224.50	$224.50	$224.50
Purchase #3	$189.74	3.436%	$196.2595	$196.26	$196.25	$196.30
Purchase #4	$119.65	8.144%	$129.3943	$129.39	$129.40	$129.40
Purchase #5	$204.71	12.585%	$230.4728	$230.47	$230.45	$230.50
Purchase #6	$5.97	13.755%	$6.7912	$6.79	$6.80	$6.80
Purchase #7	$146.94	7.741%	$158.3146	$158.31	$158.30	$158.30
7 purchase totals =	$949.03		$1,016.2619	$1,016.25	$1,016.25	$1,016.30