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	$113.93	4.175%	$118.6866	$118.69	$118.70	$118.70
Purchase #2	$46.61	10.484%	$51.4966	$51.50	$51.50	$51.50
Purchase #3	$244.77	3.433%	$253.173	$253.17	$253.15	$253.20
Purchase #4	$161.52	10.768%	$178.9125	$178.91	$178.90	$178.90
Purchase #5	$248.43	6.427%	$264.3966	$264.40	$264.40	$264.40
Purchase #6	$66.34	4.643%	$69.4202	$69.42	$69.40	$69.40
Purchase #7	$179.88	6.104%	$190.8599	$190.86	$190.85	$190.90
7 purchase totals =	$1,061.48		$1,126.9454	$1,126.95	$1,126.90	$1,127.00