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	$223.60	13.773%	$254.3964	$254.40	$254.40	$254.40
Purchase #2	$177.91	4.195%	$185.3733	$185.37	$185.35	$185.40
Purchase #3	$53.89	3.863%	$55.9718	$55.97	$55.95	$56.00
Purchase #4	$114.73	9.671%	$125.8255	$125.83	$125.85	$125.80
Purchase #5	$156.93	6.812%	$167.6201	$167.62	$167.60	$167.60
Purchase #6	$113.37	11.559%	$126.4744	$126.47	$126.45	$126.50
Purchase #7	$104.40	4.668%	$109.2734	$109.27	$109.25	$109.30
7 purchase totals =	$944.83		$1,024.9349	$1,024.93	$1,024.85	$1,025.00