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	$174.26	10.544%	$192.634	$192.63	$192.65	$192.60
Purchase #2	$54.30	8.822%	$59.0903	$59.09	$59.10	$59.10
Purchase #3	$223.82	4.307%	$233.4599	$233.46	$233.45	$233.50
Purchase #4	$99.70	10.809%	$110.4766	$110.48	$110.50	$110.50
Purchase #5	$211.69	6.142%	$224.692	$224.69	$224.70	$224.70
Purchase #6	$49.51	4.423%	$51.6998	$51.70	$51.70	$51.70
Purchase #7	$61.97	13.179%	$70.137	$70.14	$70.15	$70.10
7 purchase totals =	$875.25		$942.1896	$942.19	$942.25	$942.20