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	$213.48	11.323%	$237.6523	$237.65	$237.65	$237.70
Purchase #2	$116.83	9.211%	$127.5912	$127.59	$127.60	$127.60
Purchase #3	$66.84	6.379%	$71.1037	$71.10	$71.10	$71.10
Purchase #4	$234.63	4.322%	$244.7707	$244.77	$244.75	$244.80
Purchase #5	$36.40	11.181%	$40.4699	$40.47	$40.45	$40.50
Purchase #6	$160.71	13.607%	$182.5778	$182.58	$182.60	$182.60
Purchase #7	$70.93	11.388%	$79.0075	$79.01	$79.00	$79.00
7 purchase totals =	$899.82		$983.1731	$983.17	$983.15	$983.30