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	$103.46	10.787%	$114.6202	$114.62	$114.60	$114.60
Purchase #2	$185.33	13.245%	$209.877	$209.88	$209.90	$209.90
Purchase #3	$59.40	13.237%	$67.2628	$67.26	$67.25	$67.30
Purchase #4	$33.28	10.570%	$36.7977	$36.80	$36.80	$36.80
Purchase #5	$248.37	10.822%	$275.2486	$275.25	$275.25	$275.20
Purchase #6	$110.88	5.362%	$116.8254	$116.83	$116.85	$116.80
Purchase #7	$210.53	12.758%	$237.3894	$237.39	$237.40	$237.40
7 purchase totals =	$951.25		$1,058.0211	$1,058.03	$1,058.05	$1,058.00