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	$185.73	13.640%	$211.0636	$211.06	$211.05	$211.10
Purchase #2	$192.62	6.682%	$205.4909	$205.49	$205.50	$205.50
Purchase #3	$5.68	10.362%	$6.2686	$6.27	$6.25	$6.30
Purchase #4	$112.70	4.823%	$118.1355	$118.14	$118.15	$118.10
Purchase #5	$18.98	6.810%	$20.2725	$20.27	$20.25	$20.30
Purchase #6	$155.82	12.234%	$174.883	$174.88	$174.90	$174.90
Purchase #7	$151.90	4.699%	$159.0378	$159.04	$159.05	$159.00
7 purchase totals =	$823.43		$895.1519	$895.15	$895.15	$895.20