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	$56.59	7.158%	$60.6407	$60.64	$60.65	$60.60
Purchase #2	$238.95	6.498%	$254.477	$254.48	$254.50	$254.50
Purchase #3	$32.80	11.372%	$36.53	$36.53	$36.55	$36.50
Purchase #4	$56.51	8.550%	$61.3416	$61.34	$61.35	$61.30
Purchase #5	$96.94	12.695%	$109.2465	$109.25	$109.25	$109.20
Purchase #6	$17.87	10.153%	$19.6843	$19.68	$19.70	$19.70
Purchase #7	$168.30	10.260%	$185.5676	$185.57	$185.55	$185.60
7 purchase totals =	$667.96		$727.4877	$727.49	$727.55	$727.40