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	$215.42	4.545%	$225.2108	$225.21	$225.20	$225.20
Purchase #2	$56.32	5.325%	$59.319	$59.32	$59.30	$59.30
Purchase #3	$244.98	5.811%	$259.2158	$259.22	$259.20	$259.20
Purchase #4	$97.95	6.704%	$104.5166	$104.52	$104.50	$104.50
Purchase #5	$89.82	10.693%	$99.4245	$99.42	$99.40	$99.40
Purchase #6	$194.47	3.549%	$201.3717	$201.37	$201.35	$201.40
Purchase #7	$68.38	13.843%	$77.8458	$77.85	$77.85	$77.80
7 purchase totals =	$967.34		$1,026.9042	$1,026.91	$1,026.80	$1,026.80