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	$221.74	11.236%	$246.6547	$246.65	$246.65	$246.70
Purchase #2	$122.46	4.279%	$127.7001	$127.70	$127.70	$127.70
Purchase #3	$9.69	9.668%	$10.6268	$10.63	$10.65	$10.60
Purchase #4	$173.88	6.106%	$184.4971	$184.50	$184.50	$184.50
Purchase #5	$233.46	4.813%	$244.6964	$244.70	$244.70	$244.70
Purchase #6	$68.56	4.395%	$71.5732	$71.57	$71.55	$71.60
Purchase #7	$189.66	5.775%	$200.6129	$200.61	$200.60	$200.60
7 purchase totals =	$1,019.45		$1,086.3612	$1,086.36	$1,086.35	$1,086.40