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	$229.75	8.362%	$248.9617	$248.96	$248.95	$249.00
Purchase #2	$9.71	5.743%	$10.2676	$10.27	$10.25	$10.30
Purchase #3	$116.81	9.852%	$128.3181	$128.32	$128.30	$128.30
Purchase #4	$89.68	11.444%	$99.943	$99.94	$99.95	$99.90
Purchase #5	$109.62	5.324%	$115.4562	$115.46	$115.45	$115.50
Purchase #6	$233.80	3.762%	$242.5956	$242.60	$242.60	$242.60
Purchase #7	$191.25	4.780%	$200.3918	$200.39	$200.40	$200.40
7 purchase totals =	$980.62		$1,045.9340	$1,045.94	$1,045.90	$1,046.00