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	$204.46	3.240%	$211.0845	$211.08	$211.10	$211.10
Purchase #2	$84.35	7.315%	$90.5202	$90.52	$90.50	$90.50
Purchase #3	$191.90	7.847%	$206.9584	$206.96	$206.95	$207.00
Purchase #4	$233.55	12.310%	$262.3	$262.30	$262.30	$262.30
Purchase #5	$188.62	6.160%	$200.239	$200.24	$200.25	$200.20
Purchase #6	$79.47	13.152%	$89.9219	$89.92	$89.90	$89.90
Purchase #7	$137.47	5.284%	$144.7339	$144.73	$144.75	$144.70
7 purchase totals =	$1,119.82		$1,205.7579	$1,205.75	$1,205.75	$1,205.70