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	$107.48	4.149%	$111.9393	$111.94	$111.95	$111.90
Purchase #2	$208.51	4.577%	$218.0535	$218.05	$218.05	$218.10
Purchase #3	$89.39	13.522%	$101.4773	$101.48	$101.50	$101.50
Purchase #4	$186.54	5.296%	$196.4192	$196.42	$196.40	$196.40
Purchase #5	$16.91	4.704%	$17.7054	$17.71	$17.70	$17.70
Purchase #6	$27.83	8.139%	$30.0951	$30.10	$30.10	$30.10
Purchase #7	$99.69	12.296%	$111.9479	$111.95	$111.95	$111.90
7 purchase totals =	$736.35		$787.6377	$787.65	$787.65	$787.60