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	$167.52	13.185%	$189.6075	$189.61	$189.60	$189.60
Purchase #2	$192.56	10.239%	$212.2762	$212.28	$212.30	$212.30
Purchase #3	$166.89	7.619%	$179.6053	$179.61	$179.60	$179.60
Purchase #4	$17.71	3.242%	$18.2842	$18.28	$18.30	$18.30
Purchase #5	$165.35	11.173%	$183.8246	$183.82	$183.80	$183.80
Purchase #6	$138.26	4.549%	$144.5494	$144.55	$144.55	$144.50
Purchase #7	$162.58	10.635%	$179.8704	$179.87	$179.85	$179.90
7 purchase totals =	$1,010.87		$1,108.0176	$1,108.02	$1,108.00	$1,108.00