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	$107.28	3.818%	$111.376	$111.38	$111.40	$111.40
Purchase #2	$207.77	13.295%	$235.393	$235.39	$235.40	$235.40
Purchase #3	$185.53	4.706%	$194.261	$194.26	$194.25	$194.30
Purchase #4	$116.77	7.200%	$125.1774	$125.18	$125.20	$125.20
Purchase #5	$226.94	12.536%	$255.3892	$255.39	$255.40	$255.40
Purchase #6	$58.91	3.359%	$60.8888	$60.89	$60.90	$60.90
Purchase #7	$116.98	8.847%	$127.3292	$127.33	$127.35	$127.30
7 purchase totals =	$1,020.18		$1,109.8146	$1,109.82	$1,109.90	$1,109.90