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	$241.65	10.618%	$267.3084	$267.31	$267.30	$267.30
Purchase #2	$80.64	12.198%	$90.4765	$90.48	$90.50	$90.50
Purchase #3	$5.33	3.828%	$5.534	$5.53	$5.55	$5.50
Purchase #4	$144.70	6.365%	$153.9102	$153.91	$153.90	$153.90
Purchase #5	$78.79	13.180%	$89.1745	$89.17	$89.15	$89.20
Purchase #6	$210.85	11.382%	$234.8489	$234.85	$234.85	$234.80
Purchase #7	$229.47	10.852%	$254.3721	$254.37	$254.35	$254.40
7 purchase totals =	$991.43		$1,095.6246	$1,095.62	$1,095.60	$1,095.60