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	$181.34	10.159%	$199.7623	$199.76	$199.75	$199.80
Purchase #2	$185.57	12.434%	$208.6438	$208.64	$208.65	$208.60
Purchase #3	$38.97	13.640%	$44.2855	$44.29	$44.30	$44.30
Purchase #4	$142.86	6.152%	$151.6487	$151.65	$151.65	$151.60
Purchase #5	$60.77	8.468%	$65.916	$65.92	$65.90	$65.90
Purchase #6	$222.42	12.565%	$250.3671	$250.37	$250.35	$250.40
Purchase #7	$96.50	5.360%	$101.6724	$101.67	$101.65	$101.70
7 purchase totals =	$928.43		$1,022.2958	$1,022.30	$1,022.25	$1,022.30