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	$192.82	13.339%	$218.5403	$218.54	$218.55	$218.50
Purchase #2	$203.82	3.784%	$211.5325	$211.53	$211.55	$211.50
Purchase #3	$29.30	10.194%	$32.2868	$32.29	$32.30	$32.30
Purchase #4	$81.71	5.286%	$86.0292	$86.03	$86.05	$86.00
Purchase #5	$232.25	9.512%	$254.3416	$254.34	$254.35	$254.30
Purchase #6	$27.53	4.297%	$28.713	$28.71	$28.70	$28.70
Purchase #7	$177.51	13.113%	$200.7869	$200.79	$200.80	$200.80
7 purchase totals =	$944.94		$1,032.2303	$1,032.23	$1,032.30	$1,032.10