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	$95.27	10.849%	$105.6058	$105.61	$105.60	$105.60
Purchase #2	$40.38	13.187%	$45.7049	$45.70	$45.70	$45.70
Purchase #3	$164.70	3.401%	$170.3014	$170.30	$170.30	$170.30
Purchase #4	$216.35	7.829%	$233.288	$233.29	$233.30	$233.30
Purchase #5	$222.40	9.272%	$243.0209	$243.02	$243.00	$243.00
Purchase #6	$62.82	11.485%	$70.0349	$70.03	$70.05	$70.00
Purchase #7	$13.74	6.177%	$14.5887	$14.59	$14.60	$14.60
7 purchase totals =	$815.66		$882.5446	$882.54	$882.55	$882.50