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	$91.61	5.636%	$96.7731	$96.77	$96.75	$96.80
Purchase #2	$159.72	4.203%	$166.433	$166.43	$166.45	$166.40
Purchase #3	$172.90	13.778%	$196.7222	$196.72	$196.70	$196.70
Purchase #4	$218.67	12.732%	$246.5111	$246.51	$246.50	$246.50
Purchase #5	$25.84	4.702%	$27.055	$27.06	$27.05	$27.10
Purchase #6	$155.47	13.748%	$176.844	$176.84	$176.85	$176.80
Purchase #7	$227.71	6.338%	$242.1423	$242.14	$242.15	$242.10
7 purchase totals =	$1,051.92		$1,152.4807	$1,152.47	$1,152.45	$1,152.40