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	$193.46	9.405%	$211.6549	$211.65	$211.65	$211.70
Purchase #2	$71.31	9.593%	$78.1508	$78.15	$78.15	$78.20
Purchase #3	$214.92	6.384%	$228.6405	$228.64	$228.65	$228.60
Purchase #4	$116.62	11.810%	$130.3928	$130.39	$130.40	$130.40
Purchase #5	$160.67	11.394%	$178.9767	$178.98	$179.00	$179.00
Purchase #6	$236.57	8.360%	$256.3473	$256.35	$256.35	$256.30
Purchase #7	$83.56	5.664%	$88.2928	$88.29	$88.30	$88.30
7 purchase totals =	$1,077.11		$1,172.4558	$1,172.45	$1,172.50	$1,172.50