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	$101.68	9.231%	$111.0661	$111.07	$111.05	$111.10
Purchase #2	$234.86	9.457%	$257.0707	$257.07	$257.05	$257.10
Purchase #3	$82.40	9.688%	$90.3829	$90.38	$90.40	$90.40
Purchase #4	$83.63	6.370%	$88.9572	$88.96	$88.95	$89.00
Purchase #5	$225.44	13.122%	$255.0222	$255.02	$255.00	$255.00
Purchase #6	$179.83	13.559%	$204.2131	$204.21	$204.20	$204.20
Purchase #7	$85.68	12.827%	$96.6702	$96.67	$96.65	$96.70
7 purchase totals =	$993.52		$1,103.3824	$1,103.38	$1,103.30	$1,103.50