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	$211.74	5.718%	$223.8473	$223.85	$223.85	$223.80
Purchase #2	$111.71	6.626%	$119.1119	$119.11	$119.10	$119.10
Purchase #3	$13.52	3.149%	$13.9457	$13.95	$13.95	$13.90
Purchase #4	$205.66	3.381%	$212.6134	$212.61	$212.60	$212.60
Purchase #5	$222.93	6.525%	$237.4762	$237.48	$237.50	$237.50
Purchase #6	$98.86	12.797%	$111.5111	$111.51	$111.50	$111.50
Purchase #7	$193.44	6.265%	$205.559	$205.56	$205.55	$205.60
7 purchase totals =	$1,057.86		$1,124.0646	$1,124.07	$1,124.05	$1,124.00