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	$147.83	4.379%	$154.3035	$154.30	$154.30	$154.30
Purchase #2	$25.40	4.174%	$26.4602	$26.46	$26.45	$26.50
Purchase #3	$32.91	13.251%	$37.2709	$37.27	$37.25	$37.30
Purchase #4	$224.65	5.178%	$236.2824	$236.28	$236.30	$236.30
Purchase #5	$219.86	6.131%	$233.3396	$233.34	$233.35	$233.30
Purchase #6	$29.51	13.652%	$33.5387	$33.54	$33.55	$33.50
Purchase #7	$42.45	5.627%	$44.8387	$44.84	$44.85	$44.80
7 purchase totals =	$722.61		$766.0340	$766.03	$766.05	$766.00