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	$192.68	5.152%	$202.6069	$202.61	$202.60	$202.60
Purchase #2	$200.28	12.559%	$225.4332	$225.43	$225.45	$225.40
Purchase #3	$33.78	11.426%	$37.6397	$37.64	$37.65	$37.60
Purchase #4	$170.76	10.406%	$188.5293	$188.53	$188.55	$188.50
Purchase #5	$64.89	11.755%	$72.5178	$72.52	$72.50	$72.50
Purchase #6	$95.99	5.276%	$101.0544	$101.05	$101.05	$101.10
Purchase #7	$23.69	3.826%	$24.5964	$24.60	$24.60	$24.60
7 purchase totals =	$782.07		$852.3777	$852.38	$852.40	$852.30