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	$201.70	10.763%	$223.409	$223.41	$223.40	$223.40
Purchase #2	$66.27	7.827%	$71.457	$71.46	$71.45	$71.50
Purchase #3	$184.49	12.467%	$207.4904	$207.49	$207.50	$207.50
Purchase #4	$115.89	12.739%	$130.6532	$130.65	$130.65	$130.70
Purchase #5	$34.25	10.240%	$37.7572	$37.76	$37.75	$37.80
Purchase #6	$245.71	4.397%	$256.5139	$256.51	$256.50	$256.50
Purchase #7	$82.40	13.247%	$93.3155	$93.32	$93.30	$93.30
7 purchase totals =	$930.71		$1,020.5962	$1,020.60	$1,020.55	$1,020.70