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	$114.44	10.625%	$126.5993	$126.60	$126.60	$126.60
Purchase #2	$209.97	5.399%	$221.3063	$221.31	$221.30	$221.30
Purchase #3	$161.57	6.635%	$172.2902	$172.29	$172.30	$172.30
Purchase #4	$59.86	9.227%	$65.3833	$65.38	$65.40	$65.40
Purchase #5	$175.77	8.862%	$191.3467	$191.35	$191.35	$191.30
Purchase #6	$129.52	8.786%	$140.8996	$140.90	$140.90	$140.90
Purchase #7	$182.28	6.117%	$193.4301	$193.43	$193.45	$193.40
7 purchase totals =	$1,033.41		$1,111.2555	$1,111.26	$1,111.30	$1,111.20