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	$96.56	8.718%	$104.9781	$104.98	$105.00	$105.00
Purchase #2	$162.57	6.198%	$172.6461	$172.65	$172.65	$172.60
Purchase #3	$223.32	10.808%	$247.4564	$247.46	$247.45	$247.50
Purchase #4	$248.77	10.184%	$274.1047	$274.10	$274.10	$274.10
Purchase #5	$157.60	10.698%	$174.46	$174.46	$174.45	$174.50
Purchase #6	$249.27	11.533%	$278.0183	$278.02	$278.00	$278.00
Purchase #7	$231.31	9.695%	$253.7355	$253.74	$253.75	$253.70
7 purchase totals =	$1,369.40		$1,505.3991	$1,505.41	$1,505.40	$1,505.40