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	$216.50	7.752%	$233.2831	$233.28	$233.30	$233.30
Purchase #2	$173.59	9.169%	$189.5065	$189.51	$189.50	$189.50
Purchase #3	$224.76	6.679%	$239.7717	$239.77	$239.75	$239.80
Purchase #4	$81.96	8.732%	$89.1167	$89.12	$89.10	$89.10
Purchase #5	$78.28	11.161%	$87.0168	$87.02	$87.00	$87.00
Purchase #6	$202.78	13.162%	$229.4699	$229.47	$229.45	$229.50
Purchase #7	$93.56	8.250%	$101.2787	$101.28	$101.30	$101.30
7 purchase totals =	$1,071.43		$1,169.4434	$1,169.45	$1,169.40	$1,169.50