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	$175.51	8.772%	$190.9057	$190.91	$190.90	$190.90
Purchase #2	$234.31	3.686%	$242.9467	$242.95	$242.95	$242.90
Purchase #3	$11.76	3.175%	$12.1334	$12.13	$12.15	$12.10
Purchase #4	$31.55	6.852%	$33.7118	$33.71	$33.70	$33.70
Purchase #5	$55.92	9.497%	$61.2307	$61.23	$61.25	$61.20
Purchase #6	$227.80	7.323%	$244.4818	$244.48	$244.50	$244.50
Purchase #7	$211.44	7.564%	$227.4333	$227.43	$227.45	$227.40
7 purchase totals =	$948.29		$1,012.8434	$1,012.84	$1,012.90	$1,012.70