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	$32.86	11.470%	$36.629	$36.63	$36.65	$36.60
Purchase #2	$89.28	11.490%	$99.5383	$99.54	$99.55	$99.50
Purchase #3	$68.92	7.590%	$74.151	$74.15	$74.15	$74.20
Purchase #4	$151.51	6.129%	$160.796	$160.80	$160.80	$160.80
Purchase #5	$155.68	4.389%	$162.5128	$162.51	$162.50	$162.50
Purchase #6	$196.40	6.272%	$208.7182	$208.72	$208.70	$208.70
Purchase #7	$243.68	12.697%	$274.62	$274.62	$274.60	$274.60
7 purchase totals =	$938.33		$1,016.9653	$1,016.97	$1,016.95	$1,016.90