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	$196.48	5.397%	$207.084	$207.08	$207.10	$207.10
Purchase #2	$190.79	6.759%	$203.6855	$203.69	$203.70	$203.70
Purchase #3	$36.85	5.458%	$38.8613	$38.86	$38.85	$38.90
Purchase #4	$222.80	13.678%	$253.2746	$253.27	$253.25	$253.30
Purchase #5	$158.68	6.751%	$169.3925	$169.39	$169.40	$169.40
Purchase #6	$114.94	11.254%	$127.8753	$127.88	$127.90	$127.90
Purchase #7	$207.44	7.286%	$222.5541	$222.55	$222.55	$222.60
7 purchase totals =	$1,127.98		$1,222.7273	$1,222.72	$1,222.75	$1,222.90