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	$103.75	9.406%	$113.5087	$113.51	$113.50	$113.50
Purchase #2	$168.87	11.627%	$188.5045	$188.50	$188.50	$188.50
Purchase #3	$7.36	3.312%	$7.6038	$7.60	$7.60	$7.60
Purchase #4	$57.99	6.464%	$61.7385	$61.74	$61.75	$61.70
Purchase #5	$110.52	8.432%	$119.839	$119.84	$119.85	$119.80
Purchase #6	$92.81	13.528%	$105.3653	$105.37	$105.35	$105.40
Purchase #7	$120.30	6.315%	$127.8969	$127.90	$127.90	$127.90
7 purchase totals =	$661.60		$724.4567	$724.46	$724.45	$724.40