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	$151.34	8.375%	$164.0147	$164.01	$164.00	$164.00
Purchase #2	$55.71	8.366%	$60.3707	$60.37	$60.35	$60.40
Purchase #3	$133.70	10.873%	$148.2372	$148.24	$148.25	$148.20
Purchase #4	$64.46	8.701%	$70.0687	$70.07	$70.05	$70.10
Purchase #5	$245.38	10.619%	$271.4369	$271.44	$271.45	$271.40
Purchase #6	$144.76	4.376%	$151.0947	$151.09	$151.10	$151.10
Purchase #7	$168.42	13.610%	$191.342	$191.34	$191.35	$191.30
7 purchase totals =	$963.77		$1,056.5649	$1,056.56	$1,056.55	$1,056.50