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	$214.41	6.310%	$227.9393	$227.94	$227.95	$227.90
Purchase #2	$192.80	6.406%	$205.1508	$205.15	$205.15	$205.20
Purchase #3	$86.76	11.471%	$96.7122	$96.71	$96.70	$96.70
Purchase #4	$243.35	4.530%	$254.3738	$254.37	$254.35	$254.40
Purchase #5	$144.66	13.683%	$164.4538	$164.45	$164.45	$164.50
Purchase #6	$47.80	13.303%	$54.1588	$54.16	$54.15	$54.20
Purchase #7	$72.51	13.245%	$82.1139	$82.11	$82.10	$82.10
7 purchase totals =	$1,002.29		$1,084.9026	$1,084.89	$1,084.85	$1,085.00