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	$95.98	10.860%	$106.4034	$106.40	$106.40	$106.40
Purchase #2	$135.59	12.633%	$152.7191	$152.72	$152.70	$152.70
Purchase #3	$57.74	7.179%	$61.8852	$61.89	$61.90	$61.90
Purchase #4	$187.90	10.857%	$208.3003	$208.30	$208.30	$208.30
Purchase #5	$169.54	4.104%	$176.4979	$176.50	$176.50	$176.50
Purchase #6	$223.46	4.829%	$234.2509	$234.25	$234.25	$234.30
Purchase #7	$189.25	3.713%	$196.2769	$196.28	$196.30	$196.30
7 purchase totals =	$1,059.46		$1,136.3337	$1,136.34	$1,136.35	$1,136.40