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	$211.68	6.754%	$225.9769	$225.98	$226.00	$226.00
Purchase #2	$38.96	8.373%	$42.2221	$42.22	$42.20	$42.20
Purchase #3	$43.75	3.612%	$45.3303	$45.33	$45.35	$45.30
Purchase #4	$89.84	11.824%	$100.4627	$100.46	$100.45	$100.50
Purchase #5	$221.64	7.219%	$237.6402	$237.64	$237.65	$237.60
Purchase #6	$29.52	11.431%	$32.8944	$32.89	$32.90	$32.90
Purchase #7	$20.79	7.869%	$22.426	$22.43	$22.45	$22.40
7 purchase totals =	$656.18		$706.9526	$706.95	$707.00	$706.90