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	$60.26	3.540%	$62.3932	$62.39	$62.40	$62.40
Purchase #2	$233.53	3.412%	$241.498	$241.50	$241.50	$241.50
Purchase #3	$23.38	7.771%	$25.1969	$25.20	$25.20	$25.20
Purchase #4	$117.98	11.141%	$131.1242	$131.12	$131.10	$131.10
Purchase #5	$180.87	5.560%	$190.9264	$190.93	$190.95	$190.90
Purchase #6	$89.55	3.793%	$92.9466	$92.95	$92.95	$92.90
Purchase #7	$171.33	7.840%	$184.7623	$184.76	$184.75	$184.80
7 purchase totals =	$876.90		$928.8476	$928.85	$928.85	$928.80