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	$53.44	11.195%	$59.4226	$59.42	$59.40	$59.40
Purchase #2	$146.68	5.133%	$154.2091	$154.21	$154.20	$154.20
Purchase #3	$25.60	12.771%	$28.8694	$28.87	$28.85	$28.90
Purchase #4	$219.30	6.441%	$233.4251	$233.43	$233.45	$233.40
Purchase #5	$104.77	11.849%	$117.1842	$117.18	$117.20	$117.20
Purchase #6	$212.89	3.102%	$219.4938	$219.49	$219.50	$219.50
Purchase #7	$221.74	11.532%	$247.3111	$247.31	$247.30	$247.30
7 purchase totals =	$984.42		$1,059.9153	$1,059.91	$1,059.90	$1,059.90