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	$216.80	7.745%	$233.5912	$233.59	$233.60	$233.60
Purchase #2	$99.31	11.783%	$111.0117	$111.01	$111.00	$111.00
Purchase #3	$169.84	12.726%	$191.4538	$191.45	$191.45	$191.50
Purchase #4	$232.36	12.409%	$261.1936	$261.19	$261.20	$261.20
Purchase #5	$51.52	3.865%	$53.5112	$53.51	$53.50	$53.50
Purchase #6	$31.56	5.510%	$33.299	$33.30	$33.30	$33.30
Purchase #7	$212.36	8.136%	$229.6376	$229.64	$229.65	$229.60
7 purchase totals =	$1,013.75		$1,113.6981	$1,113.69	$1,113.70	$1,113.70