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	$233.78	4.616%	$244.5713	$244.57	$244.55	$244.60
Purchase #2	$84.75	5.399%	$89.3257	$89.33	$89.35	$89.30
Purchase #3	$14.25	7.612%	$15.3347	$15.33	$15.35	$15.30
Purchase #4	$59.98	8.773%	$65.242	$65.24	$65.25	$65.20
Purchase #5	$82.48	3.534%	$85.3948	$85.39	$85.40	$85.40
Purchase #6	$87.49	11.213%	$97.3003	$97.30	$97.30	$97.30
Purchase #7	$99.41	3.111%	$102.5026	$102.50	$102.50	$102.50
7 purchase totals =	$662.14		$699.6714	$699.66	$699.70	$699.60