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	$214.89	5.371%	$226.4317	$226.43	$226.45	$226.40
Purchase #2	$47.88	6.143%	$50.8213	$50.82	$50.80	$50.80
Purchase #3	$61.38	5.142%	$64.5362	$64.54	$64.55	$64.50
Purchase #4	$54.70	11.230%	$60.8428	$60.84	$60.85	$60.80
Purchase #5	$105.59	4.135%	$109.9561	$109.96	$109.95	$110.00
Purchase #6	$29.27	11.872%	$32.7449	$32.74	$32.75	$32.70
Purchase #7	$196.98	10.741%	$218.1376	$218.14	$218.15	$218.10
7 purchase totals =	$710.69		$763.4706	$763.47	$763.50	$763.30