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	$169.65	11.717%	$189.5279	$189.53	$189.55	$189.50
Purchase #2	$158.53	11.529%	$176.8069	$176.81	$176.80	$176.80
Purchase #3	$154.38	3.356%	$159.561	$159.56	$159.55	$159.60
Purchase #4	$55.31	7.801%	$59.6247	$59.62	$59.60	$59.60
Purchase #5	$151.33	5.570%	$159.7591	$159.76	$159.75	$159.80
Purchase #6	$64.78	9.781%	$71.1161	$71.12	$71.10	$71.10
Purchase #7	$242.84	6.536%	$258.712	$258.71	$258.70	$258.70
7 purchase totals =	$996.82		$1,075.1077	$1,075.11	$1,075.05	$1,075.10