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	$106.34	4.690%	$111.3273	$111.33	$111.35	$111.30
Purchase #2	$32.38	3.116%	$33.389	$33.39	$33.40	$33.40
Purchase #3	$12.59	11.660%	$14.058	$14.06	$14.05	$14.10
Purchase #4	$106.77	7.869%	$115.1717	$115.17	$115.15	$115.20
Purchase #5	$215.45	7.168%	$230.8935	$230.89	$230.90	$230.90
Purchase #6	$48.75	10.519%	$53.878	$53.88	$53.90	$53.90
Purchase #7	$72.25	6.569%	$76.9961	$77.00	$77.00	$77.00
7 purchase totals =	$594.53		$635.7136	$635.72	$635.75	$635.80