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	$151.98	13.798%	$172.9502	$172.95	$172.95	$173.00
Purchase #2	$210.27	4.485%	$219.7006	$219.70	$219.70	$219.70
Purchase #3	$170.76	6.412%	$181.7091	$181.71	$181.70	$181.70
Purchase #4	$74.56	10.262%	$82.2113	$82.21	$82.20	$82.20
Purchase #5	$167.60	3.148%	$172.876	$172.88	$172.90	$172.90
Purchase #6	$241.89	8.278%	$261.9137	$261.91	$261.90	$261.90
Purchase #7	$34.35	3.674%	$35.612	$35.61	$35.60	$35.60
7 purchase totals =	$1,051.41		$1,126.9729	$1,126.97	$1,126.95	$1,127.00