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	$173.72	12.675%	$195.739	$195.74	$195.75	$195.70
Purchase #2	$150.73	5.820%	$159.5025	$159.50	$159.50	$159.50
Purchase #3	$150.85	12.428%	$169.5976	$169.60	$169.60	$169.60
Purchase #4	$155.87	13.664%	$177.1681	$177.17	$177.15	$177.20
Purchase #5	$91.74	9.735%	$100.6709	$100.67	$100.65	$100.70
Purchase #6	$130.40	13.596%	$148.1292	$148.13	$148.15	$148.10
Purchase #7	$79.52	13.775%	$90.4739	$90.47	$90.45	$90.50
7 purchase totals =	$932.83		$1,041.2812	$1,041.28	$1,041.25	$1,041.30