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	$174.90	7.696%	$188.3603	$188.36	$188.35	$188.40
Purchase #2	$78.72	6.268%	$83.6542	$83.65	$83.65	$83.70
Purchase #3	$35.62	3.429%	$36.8414	$36.84	$36.85	$36.80
Purchase #4	$116.38	4.814%	$121.9825	$121.98	$122.00	$122.00
Purchase #5	$128.32	6.370%	$136.494	$136.49	$136.50	$136.50
Purchase #6	$52.49	12.535%	$59.0696	$59.07	$59.05	$59.10
Purchase #7	$94.27	6.219%	$100.1327	$100.13	$100.15	$100.10
7 purchase totals =	$680.70		$726.5347	$726.52	$726.55	$726.60