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	$13.93	4.328%	$14.5329	$14.53	$14.55	$14.50
Purchase #2	$55.46	3.766%	$57.5486	$57.55	$57.55	$57.50
Purchase #3	$18.43	7.152%	$19.7481	$19.75	$19.75	$19.70
Purchase #4	$19.25	12.683%	$21.6915	$21.69	$21.70	$21.70
Purchase #5	$201.36	10.409%	$222.3196	$222.32	$222.30	$222.30
Purchase #6	$56.47	10.621%	$62.4677	$62.47	$62.45	$62.50
Purchase #7	$185.37	5.427%	$195.43	$195.43	$195.45	$195.40
7 purchase totals =	$550.27		$593.7384	$593.74	$593.75	$593.60