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	$232.43	12.793%	$262.1648	$262.16	$262.15	$262.20
Purchase #2	$44.75	6.778%	$47.7832	$47.78	$47.80	$47.80
Purchase #3	$99.85	13.765%	$113.5944	$113.59	$113.60	$113.60
Purchase #4	$104.94	11.171%	$116.6628	$116.66	$116.65	$116.70
Purchase #5	$193.88	8.153%	$209.687	$209.69	$209.70	$209.70
Purchase #6	$119.34	6.697%	$127.3322	$127.33	$127.35	$127.30
Purchase #7	$123.62	3.155%	$127.5202	$127.52	$127.50	$127.50
7 purchase totals =	$918.81		$1,004.7446	$1,004.73	$1,004.75	$1,004.80