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	$184.33	6.303%	$195.9483	$195.95	$195.95	$195.90
Purchase #2	$34.39	10.313%	$37.9366	$37.94	$37.95	$37.90
Purchase #3	$31.67	11.729%	$35.3846	$35.38	$35.40	$35.40
Purchase #4	$33.94	10.613%	$37.5421	$37.54	$37.55	$37.50
Purchase #5	$134.98	7.486%	$145.0846	$145.08	$145.10	$145.10
Purchase #6	$137.48	5.222%	$144.6592	$144.66	$144.65	$144.70
Purchase #7	$79.63	3.409%	$82.3446	$82.34	$82.35	$82.30
7 purchase totals =	$636.42		$678.9000	$678.89	$678.95	$678.80