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	$244.71	8.244%	$264.8839	$264.88	$264.90	$264.90
Purchase #2	$93.30	11.823%	$104.3309	$104.33	$104.35	$104.30
Purchase #3	$73.73	5.760%	$77.9768	$77.98	$78.00	$78.00
Purchase #4	$138.93	11.637%	$155.0973	$155.10	$155.10	$155.10
Purchase #5	$162.59	6.156%	$172.599	$172.60	$172.60	$172.60
Purchase #6	$216.58	12.566%	$243.7954	$243.80	$243.80	$243.80
Purchase #7	$32.89	3.614%	$34.0786	$34.08	$34.10	$34.10
7 purchase totals =	$962.73		$1,052.7619	$1,052.77	$1,052.85	$1,052.80