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	$148.80	13.744%	$169.2511	$169.25	$169.25	$169.30
Purchase #2	$229.77	11.128%	$255.3388	$255.34	$255.35	$255.30
Purchase #3	$127.39	7.223%	$136.5914	$136.59	$136.60	$136.60
Purchase #4	$175.60	5.718%	$185.6408	$185.64	$185.65	$185.60
Purchase #5	$71.85	13.471%	$81.5289	$81.53	$81.55	$81.50
Purchase #6	$55.78	7.668%	$60.0572	$60.06	$60.05	$60.10
Purchase #7	$153.41	5.696%	$162.1482	$162.15	$162.15	$162.10
7 purchase totals =	$962.60		$1,050.5564	$1,050.56	$1,050.60	$1,050.50