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	$173.33	8.287%	$187.6939	$187.69	$187.70	$187.70
Purchase #2	$110.37	8.115%	$119.3265	$119.33	$119.35	$119.30
Purchase #3	$177.28	5.572%	$187.158	$187.16	$187.15	$187.20
Purchase #4	$64.40	11.437%	$71.7654	$71.77	$71.75	$71.80
Purchase #5	$250.72	4.649%	$262.376	$262.38	$262.40	$262.40
Purchase #6	$222.85	12.744%	$251.25	$251.25	$251.25	$251.30
Purchase #7	$72.96	13.373%	$82.7169	$82.72	$82.70	$82.70
7 purchase totals =	$1,071.91		$1,162.2867	$1,162.30	$1,162.30	$1,162.40