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	$187.95	4.666%	$196.7197	$196.72	$196.70	$196.70
Purchase #2	$183.88	6.665%	$196.1356	$196.14	$196.15	$196.10
Purchase #3	$173.87	5.628%	$183.6554	$183.66	$183.65	$183.70
Purchase #4	$147.75	12.329%	$165.9661	$165.97	$165.95	$166.00
Purchase #5	$51.43	11.278%	$57.2303	$57.23	$57.25	$57.20
Purchase #6	$198.38	4.737%	$207.7773	$207.78	$207.80	$207.80
Purchase #7	$240.69	6.138%	$255.4636	$255.46	$255.45	$255.50
7 purchase totals =	$1,183.95		$1,262.9480	$1,262.96	$1,262.95	$1,263.00