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	$154.58	5.411%	$162.9443	$162.94	$162.95	$162.90
Purchase #2	$41.45	4.513%	$43.3206	$43.32	$43.30	$43.30
Purchase #3	$163.42	13.244%	$185.0633	$185.06	$185.05	$185.10
Purchase #4	$36.29	8.287%	$39.2974	$39.30	$39.30	$39.30
Purchase #5	$149.42	3.779%	$155.0666	$155.07	$155.05	$155.10
Purchase #6	$184.52	6.502%	$196.5175	$196.52	$196.50	$196.50
Purchase #7	$57.58	12.557%	$64.8103	$64.81	$64.80	$64.80
7 purchase totals =	$787.26		$847.0200	$847.02	$846.95	$847.00