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	$229.45	5.439%	$241.9298	$241.93	$241.95	$241.90
Purchase #2	$216.31	4.836%	$226.7708	$226.77	$226.75	$226.80
Purchase #3	$211.83	8.312%	$229.4373	$229.44	$229.45	$229.40
Purchase #4	$209.40	11.292%	$233.0454	$233.05	$233.05	$233.00
Purchase #5	$43.86	11.464%	$48.8881	$48.89	$48.90	$48.90
Purchase #6	$49.53	10.624%	$54.7921	$54.79	$54.80	$54.80
Purchase #7	$47.88	11.585%	$53.4269	$53.43	$53.45	$53.40
7 purchase totals =	$1,008.26		$1,088.2904	$1,088.30	$1,088.35	$1,088.20