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	$191.33	10.474%	$211.3699	$211.37	$211.35	$211.40
Purchase #2	$159.27	5.677%	$168.3118	$168.31	$168.30	$168.30
Purchase #3	$29.84	3.510%	$30.8874	$30.89	$30.90	$30.90
Purchase #4	$218.48	10.740%	$241.9448	$241.94	$241.95	$241.90
Purchase #5	$128.70	11.761%	$143.8364	$143.84	$143.85	$143.80
Purchase #6	$195.54	10.729%	$216.5195	$216.52	$216.50	$216.50
Purchase #7	$137.92	11.711%	$154.0718	$154.07	$154.05	$154.10
7 purchase totals =	$1,061.08		$1,166.9416	$1,166.94	$1,166.90	$1,166.90