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	$191.99	10.859%	$212.8382	$212.84	$212.85	$212.80
Purchase #2	$230.52	11.231%	$256.4097	$256.41	$256.40	$256.40
Purchase #3	$31.37	4.168%	$32.6775	$32.68	$32.70	$32.70
Purchase #4	$148.61	6.631%	$158.4643	$158.46	$158.45	$158.50
Purchase #5	$191.51	10.469%	$211.5592	$211.56	$211.55	$211.60
Purchase #6	$161.84	3.675%	$167.7876	$167.79	$167.80	$167.80
Purchase #7	$37.83	10.776%	$41.9066	$41.91	$41.90	$41.90
7 purchase totals =	$993.67		$1,081.6431	$1,081.65	$1,081.65	$1,081.70