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	$161.65	11.783%	$180.6972	$180.70	$180.70	$180.70
Purchase #2	$180.51	8.795%	$196.3859	$196.39	$196.40	$196.40
Purchase #3	$48.46	7.830%	$52.2544	$52.25	$52.25	$52.30
Purchase #4	$52.79	8.624%	$57.3426	$57.34	$57.35	$57.30
Purchase #5	$127.71	11.316%	$142.1617	$142.16	$142.15	$142.20
Purchase #6	$120.70	11.658%	$134.7712	$134.77	$134.75	$134.80
Purchase #7	$220.98	10.660%	$244.5365	$244.54	$244.55	$244.50
7 purchase totals =	$912.80		$1,008.1495	$1,008.15	$1,008.15	$1,008.20