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	$65.41	11.541%	$72.959	$72.96	$72.95	$73.00
Purchase #2	$215.32	6.314%	$228.9153	$228.92	$228.90	$228.90
Purchase #3	$91.94	9.491%	$100.666	$100.67	$100.65	$100.70
Purchase #4	$172.78	9.267%	$188.7915	$188.79	$188.80	$188.80
Purchase #5	$195.87	11.633%	$218.6556	$218.66	$218.65	$218.70
Purchase #6	$114.32	7.639%	$123.0529	$123.05	$123.05	$123.10
Purchase #7	$230.87	10.573%	$255.2799	$255.28	$255.30	$255.30
7 purchase totals =	$1,086.51		$1,188.3202	$1,188.33	$1,188.30	$1,188.50