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	$6.96	5.333%	$7.3312	$7.33	$7.35	$7.30
Purchase #2	$20.57	5.242%	$21.6483	$21.65	$21.65	$21.60
Purchase #3	$110.64	3.610%	$114.6341	$114.63	$114.65	$114.60
Purchase #4	$112.50	9.479%	$123.1639	$123.16	$123.15	$123.20
Purchase #5	$250.50	4.675%	$262.2109	$262.21	$262.20	$262.20
Purchase #6	$243.72	8.200%	$263.705	$263.71	$263.70	$263.70
Purchase #7	$250.74	7.421%	$269.3474	$269.35	$269.35	$269.30
7 purchase totals =	$995.63		$1,062.0408	$1,062.04	$1,062.05	$1,061.90