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	$165.85	5.687%	$175.2819	$175.28	$175.30	$175.30
Purchase #2	$132.36	12.233%	$148.5516	$148.55	$148.55	$148.60
Purchase #3	$62.57	13.362%	$70.9306	$70.93	$70.95	$70.90
Purchase #4	$19.31	7.202%	$20.7007	$20.70	$20.70	$20.70
Purchase #5	$172.91	9.199%	$188.816	$188.82	$188.80	$188.80
Purchase #6	$187.28	11.813%	$209.4034	$209.40	$209.40	$209.40
Purchase #7	$239.37	3.548%	$247.8628	$247.86	$247.85	$247.90
7 purchase totals =	$979.65		$1,061.5470	$1,061.54	$1,061.55	$1,061.60