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	$103.73	4.235%	$108.123	$108.12	$108.10	$108.10
Purchase #2	$94.54	6.534%	$100.7172	$100.72	$100.70	$100.70
Purchase #3	$136.32	9.223%	$148.8928	$148.89	$148.90	$148.90
Purchase #4	$147.37	10.251%	$162.4769	$162.48	$162.50	$162.50
Purchase #5	$160.62	12.221%	$180.2494	$180.25	$180.25	$180.20
Purchase #6	$137.77	7.559%	$148.184	$148.18	$148.20	$148.20
Purchase #7	$202.60	4.579%	$211.8771	$211.88	$211.90	$211.90
7 purchase totals =	$982.95		$1,060.5204	$1,060.52	$1,060.55	$1,060.50