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	$54.69	8.144%	$59.144	$59.14	$59.15	$59.10
Purchase #2	$107.86	7.311%	$115.7456	$115.75	$115.75	$115.70
Purchase #3	$212.54	10.250%	$234.3254	$234.33	$234.35	$234.30
Purchase #4	$176.66	7.372%	$189.6834	$189.68	$189.70	$189.70
Purchase #5	$80.26	11.576%	$89.5509	$89.55	$89.55	$89.60
Purchase #6	$213.87	8.625%	$232.3163	$232.32	$232.30	$232.30
Purchase #7	$127.35	10.740%	$141.0274	$141.03	$141.05	$141.00
7 purchase totals =	$973.23		$1,061.7930	$1,061.80	$1,061.85	$1,061.70