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	$162.64	13.849%	$185.164	$185.16	$185.15	$185.20
Purchase #2	$53.97	13.454%	$61.2311	$61.23	$61.25	$61.20
Purchase #3	$189.98	11.213%	$211.2825	$211.28	$211.30	$211.30
Purchase #4	$241.59	11.538%	$269.4647	$269.46	$269.45	$269.50
Purchase #5	$217.71	8.211%	$235.5862	$235.59	$235.60	$235.60
Purchase #6	$245.79	10.585%	$271.8069	$271.81	$271.80	$271.80
Purchase #7	$157.83	6.805%	$168.5703	$168.57	$168.55	$168.60
7 purchase totals =	$1,269.51		$1,403.1057	$1,403.10	$1,403.10	$1,403.20