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	$223.29	4.742%	$233.8784	$233.88	$233.90	$233.90
Purchase #2	$174.60	4.540%	$182.5268	$182.53	$182.55	$182.50
Purchase #3	$174.60	4.537%	$182.5216	$182.52	$182.50	$182.50
Purchase #4	$45.38	3.562%	$46.9964	$47.00	$47.00	$47.00
Purchase #5	$143.45	3.607%	$148.6242	$148.62	$148.60	$148.60
Purchase #6	$65.39	6.253%	$69.4788	$69.48	$69.50	$69.50
Purchase #7	$146.68	13.621%	$166.6593	$166.66	$166.65	$166.70
7 purchase totals =	$973.39		$1,030.6855	$1,030.69	$1,030.70	$1,030.70