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	$183.86	9.481%	$201.2918	$201.29	$201.30	$201.30
Purchase #2	$109.90	13.860%	$125.1321	$125.13	$125.15	$125.10
Purchase #3	$104.61	11.267%	$116.3964	$116.40	$116.40	$116.40
Purchase #4	$245.79	7.161%	$263.391	$263.39	$263.40	$263.40
Purchase #5	$9.98	6.255%	$10.6042	$10.60	$10.60	$10.60
Purchase #6	$105.82	5.263%	$111.3893	$111.39	$111.40	$111.40
Purchase #7	$115.87	10.240%	$127.7351	$127.74	$127.75	$127.70
7 purchase totals =	$875.83		$955.9399	$955.94	$956.00	$955.90