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	$103.90	9.573%	$113.8463	$113.85	$113.85	$113.80
Purchase #2	$27.70	10.607%	$30.6381	$30.64	$30.65	$30.60
Purchase #3	$93.48	6.256%	$99.3281	$99.33	$99.35	$99.30
Purchase #4	$180.98	10.842%	$200.6019	$200.60	$200.60	$200.60
Purchase #5	$86.41	13.422%	$98.008	$98.01	$98.00	$98.00
Purchase #6	$134.72	4.155%	$140.3176	$140.32	$140.30	$140.30
Purchase #7	$75.82	10.371%	$83.6833	$83.68	$83.70	$83.70
7 purchase totals =	$703.01		$766.4233	$766.43	$766.45	$766.30