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	$60.58	3.825%	$62.8972	$62.90	$62.90	$62.90
Purchase #2	$18.33	10.618%	$20.2763	$20.28	$20.30	$20.30
Purchase #3	$156.60	3.456%	$162.0121	$162.01	$162.00	$162.00
Purchase #4	$181.55	8.265%	$196.5551	$196.56	$196.55	$196.60
Purchase #5	$216.40	6.657%	$230.8057	$230.81	$230.80	$230.80
Purchase #6	$194.57	8.446%	$211.0034	$211.00	$211.00	$211.00
Purchase #7	$144.26	11.483%	$160.8254	$160.83	$160.85	$160.80
7 purchase totals =	$972.29		$1,044.3752	$1,044.39	$1,044.40	$1,044.40