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	$54.26	4.620%	$56.7668	$56.77	$56.75	$56.80
Purchase #2	$29.62	13.366%	$33.579	$33.58	$33.60	$33.60
Purchase #3	$52.91	5.298%	$55.7132	$55.71	$55.70	$55.70
Purchase #4	$169.26	7.440%	$181.8529	$181.85	$181.85	$181.90
Purchase #5	$89.54	10.156%	$98.6337	$98.63	$98.65	$98.60
Purchase #6	$227.46	5.630%	$240.266	$240.27	$240.25	$240.30
Purchase #7	$81.28	11.656%	$90.754	$90.75	$90.75	$90.80
7 purchase totals =	$704.33		$757.5656	$757.56	$757.55	$757.70