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	$196.46	5.818%	$207.89	$207.89	$207.90	$207.90
Purchase #2	$20.37	6.799%	$21.755	$21.76	$21.75	$21.80
Purchase #3	$81.90	10.520%	$90.5159	$90.52	$90.50	$90.50
Purchase #4	$152.97	12.363%	$171.8817	$171.88	$171.90	$171.90
Purchase #5	$158.51	9.553%	$173.6525	$173.65	$173.65	$173.70
Purchase #6	$158.47	4.636%	$165.8167	$165.82	$165.80	$165.80
Purchase #7	$203.53	13.593%	$231.1958	$231.20	$231.20	$231.20
7 purchase totals =	$972.21		$1,062.7076	$1,062.72	$1,062.70	$1,062.80