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	$215.27	13.789%	$244.9536	$244.95	$244.95	$245.00
Purchase #2	$96.62	5.238%	$101.681	$101.68	$101.70	$101.70
Purchase #3	$73.80	6.398%	$78.5217	$78.52	$78.50	$78.50
Purchase #4	$164.31	13.497%	$186.4869	$186.49	$186.50	$186.50
Purchase #5	$153.88	6.760%	$164.2823	$164.28	$164.30	$164.30
Purchase #6	$148.62	10.759%	$164.61	$164.61	$164.60	$164.60
Purchase #7	$199.54	6.144%	$211.7997	$211.80	$211.80	$211.80
7 purchase totals =	$1,052.04		$1,152.3352	$1,152.33	$1,152.35	$1,152.40