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	$104.52	12.215%	$117.2871	$117.29	$117.30	$117.30
Purchase #2	$11.93	7.872%	$12.8691	$12.87	$12.85	$12.90
Purchase #3	$152.31	6.153%	$161.6816	$161.68	$161.70	$161.70
Purchase #4	$85.31	6.347%	$90.7246	$90.72	$90.70	$90.70
Purchase #5	$207.33	10.641%	$229.392	$229.39	$229.40	$229.40
Purchase #6	$241.89	13.859%	$275.4135	$275.41	$275.40	$275.40
Purchase #7	$152.49	13.350%	$172.8474	$172.85	$172.85	$172.80
7 purchase totals =	$955.78		$1,060.2153	$1,060.21	$1,060.20	$1,060.20