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	$44.91	7.689%	$48.3631	$48.36	$48.35	$48.40
Purchase #2	$215.84	3.729%	$223.8887	$223.89	$223.90	$223.90
Purchase #3	$216.80	7.566%	$233.2031	$233.20	$233.20	$233.20
Purchase #4	$46.43	7.828%	$50.0645	$50.06	$50.05	$50.10
Purchase #5	$205.85	10.478%	$227.419	$227.42	$227.40	$227.40
Purchase #6	$204.88	10.178%	$225.7327	$225.73	$225.75	$225.70
Purchase #7	$103.54	10.817%	$114.7399	$114.74	$114.75	$114.70
7 purchase totals =	$1,038.25		$1,123.4110	$1,123.40	$1,123.40	$1,123.40