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	$160.85	3.267%	$166.105	$166.11	$166.10	$166.10
Purchase #2	$141.41	3.697%	$146.6379	$146.64	$146.65	$146.60
Purchase #3	$222.79	10.479%	$246.1362	$246.14	$246.15	$246.10
Purchase #4	$221.69	3.544%	$229.5467	$229.55	$229.55	$229.50
Purchase #5	$59.93	9.173%	$65.4274	$65.43	$65.45	$65.40
Purchase #6	$127.32	12.753%	$143.5571	$143.56	$143.55	$143.60
Purchase #7	$25.83	10.638%	$28.5778	$28.58	$28.60	$28.60
7 purchase totals =	$959.82		$1,025.9881	$1,026.01	$1,026.05	$1,025.90