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	$185.95	4.130%	$193.6297	$193.63	$193.65	$193.60
Purchase #2	$136.75	13.139%	$154.7176	$154.72	$154.70	$154.70
Purchase #3	$73.62	6.541%	$78.4355	$78.44	$78.45	$78.40
Purchase #4	$232.90	5.341%	$245.3392	$245.34	$245.35	$245.30
Purchase #5	$17.73	10.122%	$19.5246	$19.52	$19.50	$19.50
Purchase #6	$80.42	12.263%	$90.2819	$90.28	$90.30	$90.30
Purchase #7	$139.55	3.527%	$144.4719	$144.47	$144.45	$144.50
7 purchase totals =	$866.92		$926.4004	$926.40	$926.40	$926.30