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	$147.74	8.738%	$160.6495	$160.65	$160.65	$160.60
Purchase #2	$11.76	12.237%	$13.1991	$13.20	$13.20	$13.20
Purchase #3	$162.89	8.360%	$176.5076	$176.51	$176.50	$176.50
Purchase #4	$190.62	5.133%	$200.4045	$200.40	$200.40	$200.40
Purchase #5	$219.32	10.251%	$241.8025	$241.80	$241.80	$241.80
Purchase #6	$234.79	3.852%	$243.8341	$243.83	$243.85	$243.80
Purchase #7	$109.41	4.289%	$114.1026	$114.10	$114.10	$114.10
7 purchase totals =	$1,076.53		$1,150.4999	$1,150.49	$1,150.50	$1,150.40