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	$215.90	13.355%	$244.7334	$244.73	$244.75	$244.70
Purchase #2	$27.76	4.476%	$29.0025	$29.00	$29.00	$29.00
Purchase #3	$88.30	5.113%	$92.8148	$92.81	$92.80	$92.80
Purchase #4	$13.56	6.767%	$14.4776	$14.48	$14.50	$14.50
Purchase #5	$73.60	6.752%	$78.5695	$78.57	$78.55	$78.60
Purchase #6	$235.55	3.199%	$243.0852	$243.09	$243.10	$243.10
Purchase #7	$40.92	3.613%	$42.3984	$42.40	$42.40	$42.40
7 purchase totals =	$695.59		$745.0814	$745.08	$745.10	$745.10