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	$191.43	11.425%	$213.3009	$213.30	$213.30	$213.30
Purchase #2	$65.64	12.364%	$73.7557	$73.76	$73.75	$73.80
Purchase #3	$104.62	3.136%	$107.9009	$107.90	$107.90	$107.90
Purchase #4	$47.72	13.848%	$54.3283	$54.33	$54.35	$54.30
Purchase #5	$210.75	5.155%	$221.6142	$221.61	$221.60	$221.60
Purchase #6	$62.86	13.388%	$71.2757	$71.28	$71.30	$71.30
Purchase #7	$49.38	4.761%	$51.731	$51.73	$51.75	$51.70
7 purchase totals =	$732.40		$793.9067	$793.91	$793.95	$793.90