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	$224.73	8.463%	$243.7489	$243.75	$243.75	$243.70
Purchase #2	$105.31	5.514%	$111.1168	$111.12	$111.10	$111.10
Purchase #3	$51.41	9.714%	$56.404	$56.40	$56.40	$56.40
Purchase #4	$124.61	5.629%	$131.6243	$131.62	$131.60	$131.60
Purchase #5	$198.99	8.840%	$216.5807	$216.58	$216.60	$216.60
Purchase #6	$231.34	5.234%	$243.4483	$243.45	$243.45	$243.40
Purchase #7	$19.77	9.766%	$21.7007	$21.70	$21.70	$21.70
7 purchase totals =	$956.16		$1,024.6237	$1,024.62	$1,024.60	$1,024.50