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	$86.72	8.705%	$94.269	$94.27	$94.25	$94.30
Purchase #2	$111.36	8.456%	$120.7766	$120.78	$120.80	$120.80
Purchase #3	$31.42	12.676%	$35.4028	$35.40	$35.40	$35.40
Purchase #4	$12.97	10.258%	$14.3005	$14.30	$14.30	$14.30
Purchase #5	$115.46	10.194%	$127.23	$127.23	$127.25	$127.20
Purchase #6	$73.98	3.123%	$76.2904	$76.29	$76.30	$76.30
Purchase #7	$59.84	9.290%	$65.3991	$65.40	$65.40	$65.40
7 purchase totals =	$491.75		$533.6684	$533.67	$533.70	$533.70