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	$54.81	4.695%	$57.3833	$57.38	$57.40	$57.40
Purchase #2	$182.78	7.370%	$196.2509	$196.25	$196.25	$196.30
Purchase #3	$67.29	8.726%	$73.1617	$73.16	$73.15	$73.20
Purchase #4	$50.85	3.709%	$52.736	$52.74	$52.75	$52.70
Purchase #5	$157.78	9.256%	$172.3841	$172.38	$172.40	$172.40
Purchase #6	$194.79	10.415%	$215.0774	$215.08	$215.10	$215.10
Purchase #7	$249.60	11.254%	$277.69	$277.69	$277.70	$277.70
7 purchase totals =	$957.90		$1,044.6834	$1,044.68	$1,044.75	$1,044.80