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	$165.52	4.297%	$172.6324	$172.63	$172.65	$172.60
Purchase #2	$44.37	5.291%	$46.7176	$46.72	$46.70	$46.70
Purchase #3	$142.93	6.865%	$152.7421	$152.74	$152.75	$152.70
Purchase #4	$219.26	10.793%	$242.9247	$242.92	$242.90	$242.90
Purchase #5	$88.41	3.211%	$91.2488	$91.25	$91.25	$91.20
Purchase #6	$224.83	5.796%	$237.8611	$237.86	$237.85	$237.90
Purchase #7	$215.27	5.209%	$226.4834	$226.48	$226.50	$226.50
7 purchase totals =	$1,100.59		$1,170.6101	$1,170.60	$1,170.60	$1,170.50