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	$168.71	11.221%	$187.6409	$187.64	$187.65	$187.60
Purchase #2	$86.85	8.153%	$93.9309	$93.93	$93.95	$93.90
Purchase #3	$149.79	8.158%	$162.0099	$162.01	$162.00	$162.00
Purchase #4	$204.40	9.162%	$223.1271	$223.13	$223.15	$223.10
Purchase #5	$58.52	5.335%	$61.642	$61.64	$61.65	$61.60
Purchase #6	$82.63	7.842%	$89.1098	$89.11	$89.10	$89.10
Purchase #7	$228.69	5.399%	$241.037	$241.04	$241.05	$241.00
7 purchase totals =	$979.59		$1,058.4976	$1,058.50	$1,058.55	$1,058.30