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	$151.27	10.377%	$166.9673	$166.97	$166.95	$167.00
Purchase #2	$58.85	4.677%	$61.6024	$61.60	$61.60	$61.60
Purchase #3	$91.68	3.385%	$94.7834	$94.78	$94.80	$94.80
Purchase #4	$89.55	3.443%	$92.6332	$92.63	$92.65	$92.60
Purchase #5	$139.26	10.114%	$153.3448	$153.34	$153.35	$153.30
Purchase #6	$162.98	5.206%	$171.4647	$171.46	$171.45	$171.50
Purchase #7	$183.29	7.456%	$196.9561	$196.96	$196.95	$197.00
7 purchase totals =	$876.88		$937.7519	$937.74	$937.75	$937.80