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	$81.88	4.627%	$85.6686	$85.67	$85.65	$85.70
Purchase #2	$126.79	3.112%	$130.7357	$130.74	$130.75	$130.70
Purchase #3	$149.90	8.716%	$162.9653	$162.97	$162.95	$163.00
Purchase #4	$124.95	5.164%	$131.4024	$131.40	$131.40	$131.40
Purchase #5	$235.51	8.306%	$255.0715	$255.07	$255.05	$255.10
Purchase #6	$169.78	10.384%	$187.41	$187.41	$187.40	$187.40
Purchase #7	$92.72	6.107%	$98.3824	$98.38	$98.40	$98.40
7 purchase totals =	$981.53		$1,051.6359	$1,051.64	$1,051.60	$1,051.70