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	$185.58	5.465%	$195.7219	$195.72	$195.70	$195.70
Purchase #2	$88.75	3.503%	$91.8589	$91.86	$91.85	$91.90
Purchase #3	$160.28	10.399%	$176.9475	$176.95	$176.95	$176.90
Purchase #4	$101.47	7.805%	$109.3897	$109.39	$109.40	$109.40
Purchase #5	$118.85	7.578%	$127.8565	$127.86	$127.85	$127.90
Purchase #6	$143.59	7.805%	$154.7972	$154.80	$154.80	$154.80
Purchase #7	$28.90	7.283%	$31.0048	$31.00	$31.00	$31.00
7 purchase totals =	$827.42		$887.5765	$887.58	$887.55	$887.60