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	$63.72	13.475%	$72.3063	$72.31	$72.30	$72.30
Purchase #2	$91.87	13.469%	$104.244	$104.24	$104.25	$104.20
Purchase #3	$142.42	6.811%	$152.1202	$152.12	$152.10	$152.10
Purchase #4	$182.52	4.719%	$191.1331	$191.13	$191.15	$191.10
Purchase #5	$245.98	13.693%	$279.662	$279.66	$279.65	$279.70
Purchase #6	$8.47	11.565%	$9.4496	$9.45	$9.45	$9.40
Purchase #7	$232.80	9.307%	$254.4667	$254.47	$254.45	$254.50
7 purchase totals =	$967.78		$1,063.3819	$1,063.38	$1,063.35	$1,063.30