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	$167.59	13.707%	$190.5616	$190.56	$190.55	$190.60
Purchase #2	$31.33	5.254%	$32.9761	$32.98	$33.00	$33.00
Purchase #3	$178.91	7.362%	$192.0814	$192.08	$192.10	$192.10
Purchase #4	$236.42	13.417%	$268.1405	$268.14	$268.15	$268.10
Purchase #5	$205.41	4.519%	$214.6925	$214.69	$214.70	$214.70
Purchase #6	$91.57	9.710%	$100.4614	$100.46	$100.45	$100.50
Purchase #7	$150.40	6.411%	$160.0421	$160.04	$160.05	$160.00
7 purchase totals =	$1,061.63		$1,158.9556	$1,158.95	$1,159.00	$1,159.00