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	$98.89	12.728%	$111.4767	$111.48	$111.50	$111.50
Purchase #2	$12.51	11.550%	$13.9549	$13.95	$13.95	$14.00
Purchase #3	$174.66	7.320%	$187.4451	$187.45	$187.45	$187.40
Purchase #4	$194.45	3.107%	$200.4916	$200.49	$200.50	$200.50
Purchase #5	$51.49	5.134%	$54.1335	$54.13	$54.15	$54.10
Purchase #6	$164.78	10.487%	$182.0605	$182.06	$182.05	$182.10
Purchase #7	$191.46	9.740%	$210.1082	$210.11	$210.10	$210.10
7 purchase totals =	$888.24		$959.6705	$959.67	$959.70	$959.70