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	$191.81	5.661%	$202.6684	$202.67	$202.65	$202.70
Purchase #2	$18.52	4.320%	$19.3201	$19.32	$19.30	$19.30
Purchase #3	$47.37	12.522%	$53.3017	$53.30	$53.30	$53.30
Purchase #4	$57.27	3.679%	$59.377	$59.38	$59.40	$59.40
Purchase #5	$108.67	5.388%	$114.5251	$114.53	$114.55	$114.50
Purchase #6	$227.25	3.552%	$235.3219	$235.32	$235.30	$235.30
Purchase #7	$229.67	12.370%	$258.0802	$258.08	$258.10	$258.10
7 purchase totals =	$880.56		$942.5944	$942.60	$942.60	$942.60