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	$162.25	7.195%	$173.9239	$173.92	$173.90	$173.90
Purchase #2	$118.90	5.681%	$125.6547	$125.65	$125.65	$125.70
Purchase #3	$136.94	5.726%	$144.7812	$144.78	$144.80	$144.80
Purchase #4	$39.99	9.123%	$43.6383	$43.64	$43.65	$43.60
Purchase #5	$236.78	9.594%	$259.4967	$259.50	$259.50	$259.50
Purchase #6	$142.48	11.115%	$158.3167	$158.32	$158.30	$158.30
Purchase #7	$128.48	11.231%	$142.9096	$142.91	$142.90	$142.90
7 purchase totals =	$965.82		$1,048.7211	$1,048.72	$1,048.70	$1,048.70