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	$58.28	8.761%	$63.3859	$63.39	$63.40	$63.40
Purchase #2	$101.35	10.663%	$112.157	$112.16	$112.15	$112.20
Purchase #3	$135.99	12.188%	$152.5645	$152.56	$152.55	$152.60
Purchase #4	$239.89	9.764%	$263.3129	$263.31	$263.30	$263.30
Purchase #5	$227.37	4.605%	$237.8404	$237.84	$237.85	$237.80
Purchase #6	$99.39	6.456%	$105.8066	$105.81	$105.80	$105.80
Purchase #7	$124.61	5.135%	$131.0087	$131.01	$131.00	$131.00
7 purchase totals =	$986.88		$1,066.0760	$1,066.08	$1,066.05	$1,066.10