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	$238.47	10.530%	$263.5809	$263.58	$263.60	$263.60
Purchase #2	$188.53	4.468%	$196.9535	$196.95	$196.95	$197.00
Purchase #3	$68.54	12.403%	$77.041	$77.04	$77.05	$77.00
Purchase #4	$92.44	4.312%	$96.426	$96.43	$96.45	$96.40
Purchase #5	$215.30	13.103%	$243.5108	$243.51	$243.50	$243.50
Purchase #6	$173.67	10.312%	$191.5789	$191.58	$191.60	$191.60
Purchase #7	$35.91	3.534%	$37.1791	$37.18	$37.20	$37.20
7 purchase totals =	$1,012.86		$1,106.2702	$1,106.27	$1,106.35	$1,106.30