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	$57.37	8.732%	$62.3795	$62.38	$62.40	$62.40
Purchase #2	$75.57	4.374%	$78.8754	$78.88	$78.90	$78.90
Purchase #3	$119.82	4.766%	$125.5306	$125.53	$125.55	$125.50
Purchase #4	$109.74	7.819%	$118.3206	$118.32	$118.30	$118.30
Purchase #5	$187.60	5.629%	$198.16	$198.16	$198.15	$198.20
Purchase #6	$100.55	4.396%	$104.9702	$104.97	$104.95	$105.00
Purchase #7	$50.41	5.414%	$53.1392	$53.14	$53.15	$53.10
7 purchase totals =	$701.06		$741.3755	$741.38	$741.40	$741.40