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	$43.44	11.515%	$48.4421	$48.44	$48.45	$48.40
Purchase #2	$181.60	10.295%	$200.2957	$200.30	$200.30	$200.30
Purchase #3	$61.69	5.810%	$65.2742	$65.27	$65.25	$65.30
Purchase #4	$95.69	5.224%	$100.6888	$100.69	$100.70	$100.70
Purchase #5	$246.27	11.800%	$275.3299	$275.33	$275.35	$275.30
Purchase #6	$208.64	7.711%	$224.7282	$224.73	$224.75	$224.70
Purchase #7	$215.85	6.828%	$230.5882	$230.59	$230.60	$230.60
7 purchase totals =	$1,053.18		$1,145.3471	$1,145.35	$1,145.40	$1,145.30