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	$216.55	7.841%	$233.5297	$233.53	$233.55	$233.50
Purchase #2	$106.30	7.515%	$114.2884	$114.29	$114.30	$114.30
Purchase #3	$141.72	4.612%	$148.2561	$148.26	$148.25	$148.30
Purchase #4	$162.49	13.804%	$184.9201	$184.92	$184.90	$184.90
Purchase #5	$175.48	5.379%	$184.9191	$184.92	$184.90	$184.90
Purchase #6	$237.40	7.205%	$254.5047	$254.50	$254.50	$254.50
Purchase #7	$42.50	13.294%	$48.15	$48.15	$48.15	$48.20
7 purchase totals =	$1,082.44		$1,168.5681	$1,168.57	$1,168.55	$1,168.60