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	$163.51	11.123%	$181.6972	$181.70	$181.70	$181.70
Purchase #2	$82.63	3.629%	$85.6286	$85.63	$85.65	$85.60
Purchase #3	$19.59	13.699%	$22.2736	$22.27	$22.25	$22.30
Purchase #4	$39.80	13.821%	$45.3008	$45.30	$45.30	$45.30
Purchase #5	$69.34	3.551%	$71.8023	$71.80	$71.80	$71.80
Purchase #6	$216.92	6.254%	$230.4862	$230.49	$230.50	$230.50
Purchase #7	$77.33	6.395%	$82.2753	$82.28	$82.30	$82.30
7 purchase totals =	$669.12		$719.4640	$719.47	$719.50	$719.50