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	$191.56	9.860%	$210.4478	$210.45	$210.45	$210.40
Purchase #2	$140.47	13.107%	$158.8814	$158.88	$158.90	$158.90
Purchase #3	$209.26	5.810%	$221.418	$221.42	$221.40	$221.40
Purchase #4	$67.65	6.678%	$72.1677	$72.17	$72.15	$72.20
Purchase #5	$109.43	7.612%	$117.7598	$117.76	$117.75	$117.80
Purchase #6	$145.71	4.815%	$152.7259	$152.73	$152.75	$152.70
Purchase #7	$113.80	8.114%	$123.0337	$123.03	$123.05	$123.00
7 purchase totals =	$977.88		$1,056.4343	$1,056.44	$1,056.45	$1,056.40