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	$98.32	4.405%	$102.651	$102.65	$102.65	$102.70
Purchase #2	$238.72	12.505%	$268.5719	$268.57	$268.55	$268.60
Purchase #3	$221.86	5.139%	$233.2614	$233.26	$233.25	$233.30
Purchase #4	$82.38	12.387%	$92.5844	$92.58	$92.60	$92.60
Purchase #5	$39.56	6.679%	$42.2022	$42.20	$42.20	$42.20
Purchase #6	$78.77	13.833%	$89.6663	$89.67	$89.65	$89.70
Purchase #7	$187.48	9.144%	$204.6232	$204.62	$204.60	$204.60
7 purchase totals =	$947.09		$1,033.5604	$1,033.55	$1,033.50	$1,033.70