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	$158.71	9.812%	$174.2826	$174.28	$174.30	$174.30
Purchase #2	$127.79	4.809%	$133.9354	$133.94	$133.95	$133.90
Purchase #3	$66.61	6.472%	$70.921	$70.92	$70.90	$70.90
Purchase #4	$173.26	5.346%	$182.5225	$182.52	$182.50	$182.50
Purchase #5	$20.85	3.799%	$21.6421	$21.64	$21.65	$21.60
Purchase #6	$210.68	6.108%	$223.5483	$223.55	$223.55	$223.50
Purchase #7	$149.38	4.112%	$155.5225	$155.52	$155.50	$155.50
7 purchase totals =	$907.28		$962.3744	$962.37	$962.35	$962.20