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	$105.74	7.529%	$113.7012	$113.70	$113.70	$113.70
Purchase #2	$54.89	10.807%	$60.822	$60.82	$60.80	$60.80
Purchase #3	$229.40	11.471%	$255.7145	$255.71	$255.70	$255.70
Purchase #4	$8.49	11.392%	$9.4572	$9.46	$9.45	$9.50
Purchase #5	$154.28	5.169%	$162.2547	$162.25	$162.25	$162.30
Purchase #6	$96.37	4.572%	$100.776	$100.78	$100.80	$100.80
Purchase #7	$171.29	11.708%	$191.3446	$191.34	$191.35	$191.30
7 purchase totals =	$820.46		$894.0702	$894.06	$894.05	$894.10