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	$239.45	13.616%	$272.0535	$272.05	$272.05	$272.10
Purchase #2	$51.97	13.735%	$59.1081	$59.11	$59.10	$59.10
Purchase #3	$89.75	3.662%	$93.0366	$93.04	$93.05	$93.00
Purchase #4	$180.29	13.470%	$204.5751	$204.58	$204.60	$204.60
Purchase #5	$139.83	8.391%	$151.5631	$151.56	$151.55	$151.60
Purchase #6	$160.43	5.148%	$168.6889	$168.69	$168.70	$168.70
Purchase #7	$94.38	11.374%	$105.1148	$105.11	$105.10	$105.10
7 purchase totals =	$956.10		$1,054.1401	$1,054.14	$1,054.15	$1,054.20