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	$199.95	11.305%	$222.5543	$222.55	$222.55	$222.60
Purchase #2	$95.67	9.821%	$105.0658	$105.07	$105.05	$105.10
Purchase #3	$147.74	13.231%	$167.2875	$167.29	$167.30	$167.30
Purchase #4	$209.98	5.236%	$220.9746	$220.97	$220.95	$221.00
Purchase #5	$55.34	10.410%	$61.1009	$61.10	$61.10	$61.10
Purchase #6	$161.84	5.285%	$170.3932	$170.39	$170.40	$170.40
Purchase #7	$83.31	8.355%	$90.2706	$90.27	$90.25	$90.30
7 purchase totals =	$953.83		$1,037.6469	$1,037.64	$1,037.60	$1,037.80