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	$168.93	3.686%	$175.1568	$175.16	$175.15	$175.20
Purchase #2	$101.78	3.426%	$105.267	$105.27	$105.25	$105.30
Purchase #3	$75.80	13.179%	$85.7897	$85.79	$85.80	$85.80
Purchase #4	$78.55	6.462%	$83.6259	$83.63	$83.65	$83.60
Purchase #5	$194.55	6.150%	$206.5148	$206.51	$206.50	$206.50
Purchase #6	$139.57	8.640%	$151.6288	$151.63	$151.65	$151.60
Purchase #7	$194.39	6.784%	$207.5774	$207.58	$207.60	$207.60
7 purchase totals =	$953.57		$1,015.5604	$1,015.57	$1,015.60	$1,015.60