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	$65.47	10.820%	$72.5539	$72.55	$72.55	$72.60
Purchase #2	$153.46	12.186%	$172.1606	$172.16	$172.15	$172.20
Purchase #3	$239.48	10.109%	$263.689	$263.69	$263.70	$263.70
Purchase #4	$25.69	10.607%	$28.4149	$28.41	$28.40	$28.40
Purchase #5	$204.55	5.638%	$216.0825	$216.08	$216.10	$216.10
Purchase #6	$175.67	7.840%	$189.4425	$189.44	$189.45	$189.40
Purchase #7	$197.73	4.443%	$206.5151	$206.52	$206.50	$206.50
7 purchase totals =	$1,062.05		$1,148.8585	$1,148.85	$1,148.85	$1,148.90