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	$134.48	13.587%	$152.7518	$152.75	$152.75	$152.80
Purchase #2	$57.76	13.565%	$65.5951	$65.60	$65.60	$65.60
Purchase #3	$153.89	12.240%	$172.7261	$172.73	$172.75	$172.70
Purchase #4	$102.97	8.767%	$111.9974	$112.00	$112.00	$112.00
Purchase #5	$117.27	8.535%	$127.279	$127.28	$127.30	$127.30
Purchase #6	$16.28	6.203%	$17.2898	$17.29	$17.30	$17.30
Purchase #7	$47.45	13.560%	$53.8842	$53.88	$53.90	$53.90
7 purchase totals =	$630.10		$701.5234	$701.53	$701.60	$701.60