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	$216.97	3.557%	$224.6876	$224.69	$224.70	$224.70
Purchase #2	$230.43	4.316%	$240.3754	$240.38	$240.40	$240.40
Purchase #3	$190.37	3.787%	$197.5793	$197.58	$197.60	$197.60
Purchase #4	$229.50	5.809%	$242.8317	$242.83	$242.85	$242.80
Purchase #5	$179.25	9.790%	$196.7986	$196.80	$196.80	$196.80
Purchase #6	$206.96	7.643%	$222.778	$222.78	$222.80	$222.80
Purchase #7	$114.62	11.252%	$127.517	$127.52	$127.50	$127.50
7 purchase totals =	$1,368.10		$1,452.5676	$1,452.58	$1,452.65	$1,452.60