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	$226.63	11.495%	$252.6811	$252.68	$252.70	$252.70
Purchase #2	$190.73	12.788%	$215.1206	$215.12	$215.10	$215.10
Purchase #3	$28.66	9.655%	$31.4271	$31.43	$31.45	$31.40
Purchase #4	$144.27	5.158%	$151.7114	$151.71	$151.70	$151.70
Purchase #5	$178.42	7.293%	$191.4322	$191.43	$191.45	$191.40
Purchase #6	$190.32	3.470%	$196.9241	$196.92	$196.90	$196.90
Purchase #7	$12.51	11.614%	$13.9629	$13.96	$13.95	$14.00
7 purchase totals =	$971.54		$1,053.2594	$1,053.25	$1,053.25	$1,053.20