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	$147.86	10.765%	$163.7771	$163.78	$163.80	$163.80
Purchase #2	$191.84	12.846%	$216.4838	$216.48	$216.50	$216.50
Purchase #3	$50.76	10.763%	$56.2233	$56.22	$56.20	$56.20
Purchase #4	$92.66	10.364%	$102.2633	$102.26	$102.25	$102.30
Purchase #5	$223.30	13.549%	$253.5549	$253.55	$253.55	$253.60
Purchase #6	$99.76	11.507%	$111.2394	$111.24	$111.25	$111.20
Purchase #7	$149.58	10.663%	$165.5297	$165.53	$165.55	$165.50
7 purchase totals =	$955.76		$1,069.0715	$1,069.06	$1,069.10	$1,069.10