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	$216.75	13.161%	$245.2765	$245.28	$245.30	$245.30
Purchase #2	$196.91	8.236%	$213.1275	$213.13	$213.15	$213.10
Purchase #3	$238.31	10.693%	$263.7925	$263.79	$263.80	$263.80
Purchase #4	$39.93	7.357%	$42.8677	$42.87	$42.85	$42.90
Purchase #5	$249.82	6.601%	$266.3106	$266.31	$266.30	$266.30
Purchase #6	$230.39	5.824%	$243.8079	$243.81	$243.80	$243.80
Purchase #7	$189.52	3.518%	$196.1873	$196.19	$196.20	$196.20
7 purchase totals =	$1,361.63		$1,471.3700	$1,471.38	$1,471.40	$1,471.40