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	$109.58	4.181%	$114.1615	$114.16	$114.15	$114.20
Purchase #2	$12.44	10.515%	$13.7481	$13.75	$13.75	$13.70
Purchase #3	$9.31	9.516%	$10.1959	$10.20	$10.20	$10.20
Purchase #4	$90.86	9.304%	$99.3136	$99.31	$99.30	$99.30
Purchase #5	$39.58	5.443%	$41.7343	$41.73	$41.75	$41.70
Purchase #6	$148.30	11.705%	$165.6585	$165.66	$165.65	$165.70
Purchase #7	$158.55	12.670%	$178.6383	$178.64	$178.65	$178.60
7 purchase totals =	$568.62		$623.4502	$623.45	$623.45	$623.40