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	$168.27	10.187%	$185.4117	$185.41	$185.40	$185.40
Purchase #2	$35.79	5.693%	$37.8275	$37.83	$37.85	$37.80
Purchase #3	$146.55	6.631%	$156.2677	$156.27	$156.25	$156.30
Purchase #4	$24.95	7.465%	$26.8125	$26.81	$26.80	$26.80
Purchase #5	$46.39	13.736%	$52.7621	$52.76	$52.75	$52.80
Purchase #6	$98.92	12.624%	$111.4077	$111.41	$111.40	$111.40
Purchase #7	$194.72	9.231%	$212.6946	$212.69	$212.70	$212.70
7 purchase totals =	$715.59		$783.1838	$783.18	$783.15	$783.20