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	$169.65	13.307%	$192.2253	$192.23	$192.25	$192.20
Purchase #2	$148.50	5.536%	$156.721	$156.72	$156.70	$156.70
Purchase #3	$198.49	12.228%	$222.7614	$222.76	$222.75	$222.80
Purchase #4	$51.67	13.316%	$58.5504	$58.55	$58.55	$58.60
Purchase #5	$65.70	4.221%	$68.4732	$68.47	$68.45	$68.50
Purchase #6	$188.56	6.455%	$200.7315	$200.73	$200.75	$200.70
Purchase #7	$158.90	4.673%	$166.3254	$166.33	$166.35	$166.30
7 purchase totals =	$981.47		$1,065.7882	$1,065.79	$1,065.80	$1,065.80