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	$191.69	10.428%	$211.6794	$211.68	$211.70	$211.70
Purchase #2	$146.38	3.361%	$151.2998	$151.30	$151.30	$151.30
Purchase #3	$122.85	3.390%	$127.0146	$127.01	$127.00	$127.00
Purchase #4	$72.56	3.378%	$75.0111	$75.01	$75.00	$75.00
Purchase #5	$236.70	10.707%	$262.0435	$262.04	$262.05	$262.00
Purchase #6	$84.35	8.585%	$91.5914	$91.59	$91.60	$91.60
Purchase #7	$137.59	10.854%	$152.524	$152.52	$152.50	$152.50
7 purchase totals =	$992.12		$1,071.1638	$1,071.15	$1,071.15	$1,071.10