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	$211.75	12.461%	$238.1362	$238.14	$238.15	$238.10
Purchase #2	$233.46	13.830%	$265.7475	$265.75	$265.75	$265.70
Purchase #3	$207.39	7.659%	$223.274	$223.27	$223.25	$223.30
Purchase #4	$175.55	3.148%	$181.0763	$181.08	$181.10	$181.10
Purchase #5	$71.32	4.629%	$74.6214	$74.62	$74.60	$74.60
Purchase #6	$38.37	11.289%	$42.7016	$42.70	$42.70	$42.70
Purchase #7	$20.28	3.566%	$21.0032	$21.00	$21.00	$21.00
7 purchase totals =	$958.12		$1,046.5602	$1,046.56	$1,046.55	$1,046.50