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	$198.93	7.405%	$213.6608	$213.66	$213.65	$213.70
Purchase #2	$66.51	9.186%	$72.6196	$72.62	$72.60	$72.60
Purchase #3	$122.28	4.142%	$127.3448	$127.34	$127.35	$127.30
Purchase #4	$216.77	4.228%	$225.935	$225.94	$225.95	$225.90
Purchase #5	$143.70	13.350%	$162.884	$162.88	$162.90	$162.90
Purchase #6	$207.80	6.458%	$221.2197	$221.22	$221.20	$221.20
Purchase #7	$235.83	6.349%	$250.8028	$250.80	$250.80	$250.80
7 purchase totals =	$1,191.82		$1,274.4667	$1,274.46	$1,274.45	$1,274.40