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	$168.66	13.580%	$191.564	$191.56	$191.55	$191.60
Purchase #2	$145.81	11.506%	$162.5869	$162.59	$162.60	$162.60
Purchase #3	$74.69	3.107%	$77.0106	$77.01	$77.00	$77.00
Purchase #4	$177.91	4.450%	$185.827	$185.83	$185.85	$185.80
Purchase #5	$219.74	7.353%	$235.8975	$235.90	$235.90	$235.90
Purchase #6	$180.48	4.109%	$187.8959	$187.90	$187.90	$187.90
Purchase #7	$102.32	3.242%	$105.6372	$105.64	$105.65	$105.60
7 purchase totals =	$1,069.61		$1,146.4191	$1,146.43	$1,146.45	$1,146.40