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	$48.40	11.341%	$53.889	$53.89	$53.90	$53.90
Purchase #2	$198.57	5.456%	$209.404	$209.40	$209.40	$209.40
Purchase #3	$238.71	13.648%	$271.2891	$271.29	$271.30	$271.30
Purchase #4	$51.67	3.137%	$53.2909	$53.29	$53.30	$53.30
Purchase #5	$210.88	5.544%	$222.5712	$222.57	$222.55	$222.60
Purchase #6	$180.46	8.450%	$195.7089	$195.71	$195.70	$195.70
Purchase #7	$74.28	5.579%	$78.4241	$78.42	$78.40	$78.40
7 purchase totals =	$1,002.97		$1,084.5772	$1,084.57	$1,084.55	$1,084.60