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	$167.28	10.269%	$184.458	$184.46	$184.45	$184.50
Purchase #2	$8.35	6.139%	$8.8626	$8.86	$8.85	$8.90
Purchase #3	$151.77	4.726%	$158.9427	$158.94	$158.95	$158.90
Purchase #4	$61.92	8.600%	$67.2451	$67.25	$67.25	$67.20
Purchase #5	$159.49	6.317%	$169.565	$169.57	$169.55	$169.60
Purchase #6	$83.40	5.164%	$87.7068	$87.71	$87.70	$87.70
Purchase #7	$74.51	10.275%	$82.1659	$82.17	$82.15	$82.20
7 purchase totals =	$706.72		$758.9461	$758.96	$758.90	$759.00