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	$206.68	7.860%	$222.925	$222.93	$222.95	$222.90
Purchase #2	$178.96	11.423%	$199.4026	$199.40	$199.40	$199.40
Purchase #3	$217.65	4.763%	$228.0167	$228.02	$228.00	$228.00
Purchase #4	$218.96	13.596%	$248.7298	$248.73	$248.75	$248.70
Purchase #5	$234.89	11.479%	$261.853	$261.85	$261.85	$261.90
Purchase #6	$181.77	8.300%	$196.8569	$196.86	$196.85	$196.90
Purchase #7	$221.28	10.142%	$243.7222	$243.72	$243.70	$243.70
7 purchase totals =	$1,460.19		$1,601.5062	$1,601.51	$1,601.50	$1,601.50