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	$146.69	13.488%	$166.4755	$166.48	$166.50	$166.50
Purchase #2	$150.43	3.377%	$155.51	$155.51	$155.50	$155.50
Purchase #3	$212.98	10.429%	$235.1917	$235.19	$235.20	$235.20
Purchase #4	$89.94	5.791%	$95.1484	$95.15	$95.15	$95.10
Purchase #5	$176.86	7.428%	$189.9972	$190.00	$190.00	$190.00
Purchase #6	$134.43	8.149%	$145.3847	$145.38	$145.40	$145.40
Purchase #7	$148.98	10.787%	$165.0505	$165.05	$165.05	$165.10
7 purchase totals =	$1,060.31		$1,152.7580	$1,152.76	$1,152.80	$1,152.80