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	$148.39	7.624%	$159.7033	$159.70	$159.70	$159.70
Purchase #2	$151.83	3.830%	$157.6451	$157.65	$157.65	$157.60
Purchase #3	$90.44	6.464%	$96.286	$96.29	$96.30	$96.30
Purchase #4	$150.40	12.316%	$168.9233	$168.92	$168.90	$168.90
Purchase #5	$229.37	6.435%	$244.13	$244.13	$244.15	$244.10
Purchase #6	$109.39	12.695%	$123.2771	$123.28	$123.30	$123.30
Purchase #7	$143.53	3.431%	$148.4545	$148.45	$148.45	$148.50
7 purchase totals =	$1,023.35		$1,098.4193	$1,098.42	$1,098.45	$1,098.40