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	$196.74	7.744%	$211.9755	$211.98	$212.00	$212.00
Purchase #2	$80.32	13.533%	$91.1897	$91.19	$91.20	$91.20
Purchase #3	$100.27	5.109%	$105.3928	$105.39	$105.40	$105.40
Purchase #4	$27.26	3.183%	$28.1277	$28.13	$28.15	$28.10
Purchase #5	$145.82	4.114%	$151.819	$151.82	$151.80	$151.80
Purchase #6	$177.30	10.657%	$196.1949	$196.19	$196.20	$196.20
Purchase #7	$242.77	3.723%	$251.8083	$251.81	$251.80	$251.80
7 purchase totals =	$970.48		$1,036.5079	$1,036.51	$1,036.55	$1,036.50