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	$146.82	4.819%	$153.8953	$153.90	$153.90	$153.90
Purchase #2	$189.93	3.280%	$196.1597	$196.16	$196.15	$196.20
Purchase #3	$222.68	4.818%	$233.4087	$233.41	$233.40	$233.40
Purchase #4	$235.39	5.430%	$248.1717	$248.17	$248.15	$248.20
Purchase #5	$141.54	5.319%	$149.0685	$149.07	$149.05	$149.10
Purchase #6	$133.64	4.451%	$139.5883	$139.59	$139.60	$139.60
Purchase #7	$43.72	13.565%	$49.6506	$49.65	$49.65	$49.70
7 purchase totals =	$1,113.72		$1,169.9428	$1,169.95	$1,169.90	$1,170.10