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	$96.75	4.753%	$101.3485	$101.35	$101.35	$101.30
Purchase #2	$26.28	7.799%	$28.3296	$28.33	$28.35	$28.30
Purchase #3	$146.34	4.351%	$152.7073	$152.71	$152.70	$152.70
Purchase #4	$70.70	5.845%	$74.8324	$74.83	$74.85	$74.80
Purchase #5	$90.57	6.493%	$96.4507	$96.45	$96.45	$96.50
Purchase #6	$154.76	13.179%	$175.1558	$175.16	$175.15	$175.20
Purchase #7	$99.75	3.649%	$103.3899	$103.39	$103.40	$103.40
7 purchase totals =	$685.15		$732.2142	$732.22	$732.25	$732.20