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	$109.46	4.554%	$114.4448	$114.44	$114.45	$114.40
Purchase #2	$153.28	10.439%	$169.2809	$169.28	$169.30	$169.30
Purchase #3	$249.81	10.477%	$275.9826	$275.98	$276.00	$276.00
Purchase #4	$217.82	11.608%	$243.1045	$243.10	$243.10	$243.10
Purchase #5	$240.58	12.177%	$269.8754	$269.88	$269.90	$269.90
Purchase #6	$99.52	10.301%	$109.7716	$109.77	$109.75	$109.80
Purchase #7	$209.49	4.453%	$218.8186	$218.82	$218.80	$218.80
7 purchase totals =	$1,279.96		$1,401.2784	$1,401.27	$1,401.30	$1,401.30