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	$62.91	4.186%	$65.5434	$65.54	$65.55	$65.50
Purchase #2	$45.94	10.272%	$50.659	$50.66	$50.65	$50.70
Purchase #3	$177.32	10.470%	$195.8854	$195.89	$195.90	$195.90
Purchase #4	$193.25	13.396%	$219.1378	$219.14	$219.15	$219.10
Purchase #5	$86.88	4.147%	$90.4829	$90.48	$90.50	$90.50
Purchase #6	$215.67	12.332%	$242.2664	$242.27	$242.25	$242.30
Purchase #7	$114.28	5.385%	$120.434	$120.43	$120.45	$120.40
7 purchase totals =	$896.25		$984.4089	$984.41	$984.45	$984.40