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	$188.80	9.126%	$206.0299	$206.03	$206.05	$206.00
Purchase #2	$184.57	6.476%	$196.5228	$196.52	$196.50	$196.50
Purchase #3	$56.34	11.566%	$62.8563	$62.86	$62.85	$62.90
Purchase #4	$29.38	12.376%	$33.0161	$33.02	$33.00	$33.00
Purchase #5	$238.71	4.210%	$248.7597	$248.76	$248.75	$248.80
Purchase #6	$53.64	13.140%	$60.6883	$60.69	$60.70	$60.70
Purchase #7	$152.55	13.595%	$173.2892	$173.29	$173.30	$173.30
7 purchase totals =	$903.99		$981.1623	$981.17	$981.15	$981.20