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	$190.25	7.177%	$203.9042	$203.90	$203.90	$203.90
Purchase #2	$114.68	7.308%	$123.0608	$123.06	$123.05	$123.10
Purchase #3	$49.42	7.864%	$53.3064	$53.31	$53.30	$53.30
Purchase #4	$144.43	13.278%	$163.6074	$163.61	$163.60	$163.60
Purchase #5	$203.37	4.543%	$212.6091	$212.61	$212.60	$212.60
Purchase #6	$162.29	3.419%	$167.8387	$167.84	$167.85	$167.80
Purchase #7	$83.87	13.529%	$95.2168	$95.22	$95.20	$95.20
7 purchase totals =	$948.31		$1,019.5434	$1,019.55	$1,019.50	$1,019.50