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	$155.47	4.202%	$162.0028	$162.00	$162.00	$162.00
Purchase #2	$161.65	11.629%	$180.4483	$180.45	$180.45	$180.40
Purchase #3	$86.75	7.627%	$93.3664	$93.37	$93.35	$93.40
Purchase #4	$85.59	7.643%	$92.1316	$92.13	$92.15	$92.10
Purchase #5	$240.87	5.167%	$253.3158	$253.32	$253.30	$253.30
Purchase #6	$125.56	4.119%	$130.7318	$130.73	$130.75	$130.70
Purchase #7	$155.47	11.807%	$173.8263	$173.83	$173.85	$173.80
7 purchase totals =	$1,011.36		$1,085.8230	$1,085.83	$1,085.85	$1,085.70