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	$141.72	10.821%	$157.0555	$157.06	$157.05	$157.10
Purchase #2	$178.72	8.448%	$193.8183	$193.82	$193.80	$193.80
Purchase #3	$161.96	6.764%	$172.915	$172.92	$172.90	$172.90
Purchase #4	$63.51	12.561%	$71.4875	$71.49	$71.50	$71.50
Purchase #5	$37.74	3.168%	$38.9356	$38.94	$38.95	$38.90
Purchase #6	$134.41	7.407%	$144.3657	$144.37	$144.35	$144.40
Purchase #7	$223.79	10.429%	$247.1291	$247.13	$247.15	$247.10
7 purchase totals =	$941.85		$1,025.7067	$1,025.73	$1,025.70	$1,025.70