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	$87.49	7.634%	$94.169	$94.17	$94.15	$94.20
Purchase #2	$244.41	6.281%	$259.7614	$259.76	$259.75	$259.80
Purchase #3	$24.81	10.412%	$27.3932	$27.39	$27.40	$27.40
Purchase #4	$114.27	5.475%	$120.5263	$120.53	$120.55	$120.50
Purchase #5	$80.39	7.594%	$86.4948	$86.49	$86.50	$86.50
Purchase #6	$119.60	6.716%	$127.6323	$127.63	$127.65	$127.60
Purchase #7	$82.83	10.152%	$91.2389	$91.24	$91.25	$91.20
7 purchase totals =	$753.80		$807.2159	$807.21	$807.25	$807.20