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	$152.43	13.806%	$173.4745	$173.47	$173.45	$173.50
Purchase #2	$89.40	6.281%	$95.0152	$95.02	$95.00	$95.00
Purchase #3	$175.41	5.488%	$185.0365	$185.04	$185.05	$185.00
Purchase #4	$141.53	13.136%	$160.1214	$160.12	$160.10	$160.10
Purchase #5	$207.50	5.434%	$218.7756	$218.78	$218.80	$218.80
Purchase #6	$154.27	4.636%	$161.422	$161.42	$161.40	$161.40
Purchase #7	$28.33	12.478%	$31.865	$31.87	$31.85	$31.90
7 purchase totals =	$948.87		$1,025.7102	$1,025.72	$1,025.65	$1,025.70