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	$203.72	7.594%	$219.1905	$219.19	$219.20	$219.20
Purchase #2	$57.70	7.120%	$61.8082	$61.81	$61.80	$61.80
Purchase #3	$64.40	3.433%	$66.6109	$66.61	$66.60	$66.60
Purchase #4	$90.59	9.116%	$98.8482	$98.85	$98.85	$98.80
Purchase #5	$216.75	13.687%	$246.4166	$246.42	$246.40	$246.40
Purchase #6	$79.52	13.719%	$90.4293	$90.43	$90.45	$90.40
Purchase #7	$247.55	6.687%	$264.1037	$264.10	$264.10	$264.10
7 purchase totals =	$960.23		$1,047.4074	$1,047.41	$1,047.40	$1,047.30