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	$13.33	8.844%	$14.5089	$14.51	$14.50	$14.50
Purchase #2	$39.61	10.409%	$43.733	$43.73	$43.75	$43.70
Purchase #3	$191.52	8.136%	$207.1021	$207.10	$207.10	$207.10
Purchase #4	$38.72	3.422%	$40.045	$40.05	$40.05	$40.00
Purchase #5	$83.50	7.667%	$89.9019	$89.90	$89.90	$89.90
Purchase #6	$114.91	3.168%	$118.5503	$118.55	$118.55	$118.60
Purchase #7	$169.90	8.597%	$184.5063	$184.51	$184.50	$184.50
7 purchase totals =	$651.49		$698.3475	$698.35	$698.35	$698.30