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	$233.64	7.497%	$251.156	$251.16	$251.15	$251.20
Purchase #2	$66.33	5.231%	$69.7997	$69.80	$69.80	$69.80
Purchase #3	$174.64	12.435%	$196.3565	$196.36	$196.35	$196.40
Purchase #4	$208.68	5.227%	$219.5877	$219.59	$219.60	$219.60
Purchase #5	$151.58	5.256%	$159.547	$159.55	$159.55	$159.50
Purchase #6	$55.78	10.287%	$61.5181	$61.52	$61.50	$61.50
Purchase #7	$91.73	6.187%	$97.4053	$97.41	$97.40	$97.40
7 purchase totals =	$982.38		$1,055.3703	$1,055.39	$1,055.35	$1,055.40