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	$127.71	13.634%	$145.122	$145.12	$145.10	$145.10
Purchase #2	$135.30	12.113%	$151.6889	$151.69	$151.70	$151.70
Purchase #3	$100.69	12.120%	$112.8936	$112.89	$112.90	$112.90
Purchase #4	$159.48	7.494%	$171.4314	$171.43	$171.45	$171.40
Purchase #5	$203.79	3.473%	$210.8676	$210.87	$210.85	$210.90
Purchase #6	$29.37	10.260%	$32.3834	$32.38	$32.40	$32.40
Purchase #7	$205.54	4.374%	$214.5303	$214.53	$214.55	$214.50
7 purchase totals =	$961.88		$1,038.9172	$1,038.91	$1,038.95	$1,038.90