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	$69.35	4.586%	$72.5304	$72.53	$72.55	$72.50
Purchase #2	$79.33	7.396%	$85.1972	$85.20	$85.20	$85.20
Purchase #3	$11.53	7.174%	$12.3572	$12.36	$12.35	$12.40
Purchase #4	$159.33	4.361%	$166.2784	$166.28	$166.30	$166.30
Purchase #5	$82.86	4.522%	$86.6069	$86.61	$86.60	$86.60
Purchase #6	$146.86	6.801%	$156.8479	$156.85	$156.85	$156.80
Purchase #7	$142.66	10.743%	$157.986	$157.99	$158.00	$158.00
7 purchase totals =	$691.92		$737.8040	$737.82	$737.85	$737.80