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	$173.56	11.116%	$192.8529	$192.85	$192.85	$192.90
Purchase #2	$240.56	5.531%	$253.8654	$253.87	$253.85	$253.90
Purchase #3	$24.82	9.720%	$27.2325	$27.23	$27.25	$27.20
Purchase #4	$207.97	6.554%	$221.6004	$221.60	$221.60	$221.60
Purchase #5	$38.72	10.150%	$42.6501	$42.65	$42.65	$42.70
Purchase #6	$91.93	6.736%	$98.1224	$98.12	$98.10	$98.10
Purchase #7	$119.36	6.800%	$127.4765	$127.48	$127.50	$127.50
7 purchase totals =	$896.92		$963.8002	$963.80	$963.80	$963.90