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	$141.52	4.561%	$147.9747	$147.97	$147.95	$148.00
Purchase #2	$167.98	3.398%	$173.688	$173.69	$173.70	$173.70
Purchase #3	$41.94	13.637%	$47.6594	$47.66	$47.65	$47.70
Purchase #4	$242.69	11.850%	$271.4488	$271.45	$271.45	$271.40
Purchase #5	$115.47	10.497%	$127.5909	$127.59	$127.60	$127.60
Purchase #6	$71.75	8.721%	$78.0073	$78.01	$78.00	$78.00
Purchase #7	$35.82	3.372%	$37.0279	$37.03	$37.05	$37.00
7 purchase totals =	$817.17		$883.3970	$883.40	$883.40	$883.40