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	$188.81	4.268%	$196.8684	$196.87	$196.85	$196.90
Purchase #2	$150.30	5.207%	$158.1261	$158.13	$158.15	$158.10
Purchase #3	$119.66	7.544%	$128.6872	$128.69	$128.70	$128.70
Purchase #4	$208.81	6.641%	$222.6771	$222.68	$222.70	$222.70
Purchase #5	$228.53	5.731%	$241.6271	$241.63	$241.65	$241.60
Purchase #6	$54.69	4.695%	$57.2577	$57.26	$57.25	$57.30
Purchase #7	$66.77	9.496%	$73.1105	$73.11	$73.10	$73.10
7 purchase totals =	$1,017.57		$1,078.3541	$1,078.37	$1,078.40	$1,078.40