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	$56.34	10.774%	$62.4101	$62.41	$62.40	$62.40
Purchase #2	$199.35	5.255%	$209.8258	$209.83	$209.85	$209.80
Purchase #3	$159.87	5.323%	$168.3799	$168.38	$168.40	$168.40
Purchase #4	$105.91	13.190%	$119.8795	$119.88	$119.90	$119.90
Purchase #5	$234.85	4.380%	$245.1364	$245.14	$245.15	$245.10
Purchase #6	$199.90	8.468%	$216.8275	$216.83	$216.85	$216.80
Purchase #7	$180.88	4.455%	$188.9382	$188.94	$188.95	$188.90
7 purchase totals =	$1,137.10		$1,211.3974	$1,211.41	$1,211.50	$1,211.30