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	$42.27	3.383%	$43.7	$43.70	$43.70	$43.70
Purchase #2	$31.93	10.250%	$35.2028	$35.20	$35.20	$35.20
Purchase #3	$111.69	10.477%	$123.3918	$123.39	$123.40	$123.40
Purchase #4	$27.61	11.378%	$30.7515	$30.75	$30.75	$30.80
Purchase #5	$202.37	10.575%	$223.7706	$223.77	$223.75	$223.80
Purchase #6	$132.90	11.723%	$148.4799	$148.48	$148.50	$148.50
Purchase #7	$115.93	11.187%	$128.8991	$128.90	$128.90	$128.90
7 purchase totals =	$664.70		$734.1957	$734.19	$734.20	$734.30